postfix 向外发邮件报错 20C

使用postfix给163发邮件报错

23695120080      502 Wed Jan 16 10:34:42  admin@zhang0027.com
(connect to 163mx02.mxmail.netease.com[220.181.14.148]:25: Connection timed out)
                                         156****1085@163.com

给qq邮箱发邮件

D40CA1202EF      339 Tue Jan 15 16:31:33  admin@zhang0027.com
(connect to mx1.qq.com[2001:df6:f400::2808]:25: Cannot assign requested address)
                                         104****878@qq.com

在内网中发邮件没有问题,不能发外网

配置是按照 https://www.cnblogs.com/Dicky-Zhang/p/6084852.html 配置的

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给公司内部配置个邮件服务器,不对外。 以文章http://linuxu.blog.51cto.com/9471357/1641436/作为参考。 其间出现种种问题,一一解决。目前状态是以网页的形式可以正常使用,但是使用 outlook客户端时就不能工作,显示无法登录接收的邮件服务器。 我的postfix的main.cf文件是 compatibility_level = 2 queue_directory = /var/spool/postfix command_directory = /usr/sbin daemon_directory = /usr/libexec/postfix data_directory = /var/lib/postfix mail_owner = postfix unknown_local_recipient_reject_code = 550 debug_peer_level = 2 debugger_command = PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin ddd $daemon_directory/$process_name $process_id & sleep 5 sendmail_path = /usr/sbin/sendmail newaliases_path = /usr/bin/newaliases mailq_path = /usr/bin/mailq setgid_group = postdrop html_directory = no manpage_directory = /usr/local/man sample_directory = /etc/postfix readme_directory = no inet_protocols = ipv4 meta_directory = /etc/postfix shlib_directory = no myhostname = XTIC mydomain = mail.xtic.com myorigin = $mydomain inet_interfaces = all #mydestination = $myhostname, localhost, $mydomain, localhost.$mydomain mynetworks = 192.168.2.0/24, 127.0.0.0/8 #mynetworks = 0.0.0.0/0 alias_maps = hash:/etc/aliases smtputf8_enable = no ## postfix support smtp ## smtpd_sasl_auth_enable = yes smtpd_sasl_local_domain = '' smtpd_recipient_restrictions = permit_mynetworks,permit_sasl_authenticated,reject_unauth_destination #smtpd_recipient_restrictions = permit_mynetworks broken_sasl_auth_clients = yes smtpd_client_restrictions = permit_mynetworks,permit_sasl_authenticated #smtpd_client_restrictions = permit_mynetworks smtpd_sasl_security_options = noanonymous ## postfix support virtual ## virtual_mailbox_base = /var/mailbox virtual_mailbox_maps = mysql:/etc/postfix/mysql_virtual_mailbox_maps.cf virtual_mailbox_domains = mysql:/etc/postfix/mysql_virtual_domains_maps.cf virtual_alias_domains = virtual_alias_maps = mysql:/etc/postfix/mysql_virtual_alias_maps.cf virtual_uid_maps = static:2525 virtual_gid_maps = static:2525 virtual_transport = virtual maillog文件内容是 Sep 14 11:10:17 XTIC postfix/smtpd[5635]: connect from unknown[192.168.1.200] Sep 14 11:10:17 XTIC postfix/smtpd[5635]: DC4901C0852: client=unknown[192.168.1.200], sasl_method=LOGIN, sasl_username=zxdong@mail.xtic.com Sep 14 11:10:17 XTIC postfix/cleanup[5644]: DC4901C0852: message-id=<> Sep 14 11:10:17 XTIC postfix/smtpd[5635]: disconnect from unknown[192.168.1.200] ehlo=1 auth=1 mail=1 rcpt=1 data=1 commands=5 Sep 14 11:10:18 XTIC postfix/qmgr[28146]: DC4901C0852: from=<zxdong@mail.xtic.com>, size=546, nrcpt=1 (queue active) Sep 14 11:10:18 XTIC postfix/virtual[5646]: DC4901C0852: to=<zxdong@mail.xtic.com>, relay=virtual, delay=0.25, delays=0.17/0.03/0/0.05, dsn=2.0.0, status=sent (delivered to maildir) Sep 14 11:10:18 XTIC postfix/qmgr[28146]: DC4901C0852: removed 望哪位高人给点指点,谢谢
求助:sasl authentication 问题
各位好; 给公司内部配置个邮件服务器,不对外。 以文章http://linuxu.blog.51cto.com/9471357/1641436/作为参考。 目前出现这样的问题: [root@XTIC ~]# telnet localhost 25 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. 220 XTIC ESMTP Postfix auth login 334 VXNlcm5hbWU6 334 UGFzc3dvcmQ6 535 5.7.8 Error: authentication failed: generic failure quit 221 2.0.0 Bye Connection closed by foreign host. maillog文件显示: [root@XTIC log]# tail maillog Sep 27 15:51:41 XTIC postfix/smtpd[30876]: connect from localhost[127.0.0.1] Sep 27 15:52:06 XTIC postfix/smtpd[30876]: warning: SASL authentication failure: All-whitespace username. Sep 27 15:52:06 XTIC postfix/smtpd[30876]: warning: localhost[127.0.0.1]: SASL LOGIN authentication failed: generic failure Sep 27 15:53:42 XTIC postfix/smtpd[30876]: warning: SASL authentication failure: All-whitespace username. Sep 27 15:53:42 XTIC postfix/smtpd[30876]: warning: localhost[127.0.0.1]: SASL PLAIN authentication failed: generic failure Sep 27 15:53:53 XTIC postfix/smtpd[30876]: disconnect from localhost[127.0.0.1] Sep 27 16:55:13 XTIC postfix/smtpd[31397]: connect from localhost[127.0.0.1] Sep 27 16:55:25 XTIC postfix/smtpd[31397]: warning: SASL authentication failure: All-whitespace username. Sep 27 16:55:25 XTIC postfix/smtpd[31397]: warning: localhost[127.0.0.1]: SASL login authentication failed: generic failure Sep 27 16:55:29 XTIC postfix/smtpd[31397]: disconnect from localhost[127.0.0.1] 我的postfix的main.cf文件为: readme_directory = /usr/share/doc/postfix-2.6.6/README_FILES inet_protocols = ipv4 meta_directory = /etc/postfix shlib_directory = no myhostname = XTIC mydomain = mail.xtic.com myorigin = $mydomain inet_interfaces = all mynetworks = 192.168.2.0/24, 127.0.0.0/8 alias_maps = hash:/etc/aliases smtputf8_enable = no ## postfix support smtp ## smtpd_sasl_auth_enable = yes smtpd_sasl_local_domain = smtpd_recipient_restrictions = permit_mynetworks,permit_sasl_authenticated,reject_unauth_destination broken_sasl_auth_clients = yes smtpd_client_restrictions = permit_mynetworks,permit_sasl_authenticated smtpd_sasl_security_options = noanonymous ## postfix support virtual ## virtual_mailbox_base = /var/mailbox virtual_mailbox_maps = mysql:/etc/postfix/mysql_virtual_mailbox_maps.cf virtual_mailbox_domains = mysql:/etc/postfix/mysql_virtual_domains_maps.cf virtual_alias_domains = virtual_alias_maps = mysql:/etc/postfix/mysql_virtual_alias_maps.cf virtual_uid_maps = static:2525 virtual_gid_maps = static:2525 virtual_transport = virtual 这个问题已经困扰我很久了,网上也没有什么明确的解决方案,想请教论坛上的各位大神,有谁能给点建议,谢谢!
Linux 搭建postfix邮件服务器遇到的问题~~~急急急~~!!
http://127.0.0.1/postfixadmin/login.php 网站进入postfixAdmin,用管理员用户名密码登录后,出现 如下错误: “Not Found” “The requested URL /login.php was not found on this server.” 小弟不知道是哪里配置错误了,网上查找了很多帖子,也没能解决,急急急求大神~~~!!!
中标麒麟安装postfix遇到问题,求大神指导
postfix: warning: smtputf8_enable is true, but EAI support is not compiled in
Polish notation 程序的编写
Problem Description Reverse Polish notation (RPN) is a method for representing expressions in which the operator symbol is placed after the arguments being operated on. Polish notation, in which the operator comes before the operands, was invented in the 1920s by the Polish mathematician Jan Lucasiewicz. In the late 1950s, Australian philosopher and computer scientist Charles L. Hamblin suggested placing the operator after the operands and hence created reverse polish notation. RPN has the property that brackets are not required to represent the order of evaluation or grouping of the terms. RPN expressions are simply evaluated from left to right and this greatly simplifies the computation of the expression within computer programs. As an example, the arithmetic expression (3+4)*5 can be expressed in RPN as 3 4 + 5 *. Reverse Polish notation, also known as postfix notation, contrasts with the infix notation of standard arithmetic expressions in which the operator symbol appears between the operands. So Polish notation just as prefix notation. Now, give you a string of standard arithmetic expressions, please tell me the Polish notation and the value of expressions. Input There're have multi-case. Every case put in one line, the expressions just contain some positive integers(all less than 100, the number of integers less than 20), bi-operand operators(only have 3 kinds : +,-,*) and some brackets'(',')'. you can assume the expressions was valid. Output Each case output the Polish notation in first line, and the result of expressions was output in second line. all of the answers are no any spaces and blank line.the answer will be not exceed the 64-signed integer. Sample Input 1+2-3*(4-5) 1+2*(3-4)-5*6 Sample Output Case 1: - + 1 2 * 3 - 4 5 6 Case 2: - + 1 * 2 - 3 4 * 5 6 -31
yum install mysql-community-server 安装mysql 报错求大神帮忙!!!!
[root@11 mysql]# yum install mysql-community-server Loaded plugins: fastestmirror Setting up Install Process Loading mirror speeds from cached hostfile Resolving Dependencies --> Running transaction check ---> Package mysql-community-server.x86_64 0:8.0.16-1.el7 will be installed --> Processing Dependency: mysql-community-common(x86-64) = 8.0.16-1.el7 for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: mysql-community-client(x86-64) >= 8.0.11 for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: systemd for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: systemd for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.19)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.18)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.17)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.15)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.14)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(CXXABI_1.3.7)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(CXXABI_1.3.5)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libc.so.6(GLIBC_2.17)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libsasl2.so.3()(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Running transaction check ---> Package mysql-community-client.x86_64 0:8.0.16-1.el7 will be installed --> Processing Dependency: mysql-community-libs(x86-64) >= 8.0.11 for package: mysql-community-client-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.19)(64bit) for package: mysql-community-client-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.18)(64bit) for package: mysql-community-client-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.15)(64bit) for package: mysql-community-client-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.14)(64bit) for package: mysql-community-client-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(CXXABI_1.3.5)(64bit) for package: mysql-community-client-8.0.16-1.el7.x86_64 --> Processing Dependency: libc.so.6(GLIBC_2.14)(64bit) for package: mysql-community-client-8.0.16-1.el7.x86_64 ---> Package mysql-community-common.x86_64 0:8.0.16-1.el7 will be installed ---> Package mysql-community-server.x86_64 0:8.0.16-1.el7 will be installed --> Processing Dependency: systemd for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: systemd for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.19)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.18)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.17)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.15)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.14)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(CXXABI_1.3.7)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(CXXABI_1.3.5)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libc.so.6(GLIBC_2.17)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libsasl2.so.3()(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Running transaction check ---> Package mysql-community-client.x86_64 0:8.0.16-1.el7 will be installed --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.19)(64bit) for package: mysql-community-client-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.18)(64bit) for package: mysql-community-client-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.15)(64bit) for package: mysql-community-client-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.14)(64bit) for package: mysql-community-client-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(CXXABI_1.3.5)(64bit) for package: mysql-community-client-8.0.16-1.el7.x86_64 --> Processing Dependency: libc.so.6(GLIBC_2.14)(64bit) for package: mysql-community-client-8.0.16-1.el7.x86_64 ---> Package mysql-community-libs.x86_64 0:8.0.16-1.el7 will be installed --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.18)(64bit) for package: mysql-community-libs-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(CXXABI_1.3.5)(64bit) for package: mysql-community-libs-8.0.16-1.el7.x86_64 --> Processing Dependency: libc.so.6(GLIBC_2.14)(64bit) for package: mysql-community-libs-8.0.16-1.el7.x86_64 ---> Package mysql-community-server.x86_64 0:8.0.16-1.el7 will be installed --> Processing Dependency: systemd for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: systemd for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.19)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.18)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.17)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.15)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.14)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(CXXABI_1.3.7)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libstdc++.so.6(CXXABI_1.3.5)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libc.so.6(GLIBC_2.17)(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Processing Dependency: libsasl2.so.3()(64bit) for package: mysql-community-server-8.0.16-1.el7.x86_64 --> Finished Dependency Resolution Error: Package: mysql-community-server-8.0.16-1.el7.x86_64 (mysql80-community) Requires: libstdc++.so.6(GLIBCXX_3.4.18)(64bit) Error: Package: mysql-community-server-8.0.16-1.el7.x86_64 (mysql80-community) Requires: libstdc++.so.6(GLIBCXX_3.4.19)(64bit) Error: Package: mysql-community-client-8.0.16-1.el7.x86_64 (mysql80-community) Requires: libstdc++.so.6(GLIBCXX_3.4.15)(64bit) Error: Package: mysql-community-server-8.0.16-1.el7.x86_64 (mysql80-community) Requires: libstdc++.so.6(CXXABI_1.3.5)(64bit) Error: Package: mysql-community-client-8.0.16-1.el7.x86_64 (mysql80-community) Requires: libstdc++.so.6(GLIBCXX_3.4.14)(64bit) Error: Package: mysql-community-server-8.0.16-1.el7.x86_64 (mysql80-community) Requires: systemd Error: Package: mysql-community-libs-8.0.16-1.el7.x86_64 (mysql80-community) Requires: libstdc++.so.6(CXXABI_1.3.5)(64bit) Error: Package: mysql-community-libs-8.0.16-1.el7.x86_64 (mysql80-community) Requires: libstdc++.so.6(GLIBCXX_3.4.18)(64bit) Error: Package: mysql-community-client-8.0.16-1.el7.x86_64 (mysql80-community) Requires: libc.so.6(GLIBC_2.14)(64bit) Error: Package: mysql-community-server-8.0.16-1.el7.x86_64 (mysql80-community) Requires: libstdc++.so.6(CXXABI_1.3.7)(64bit) Error: Package: mysql-community-server-8.0.16-1.el7.x86_64 (mysql80-community) Requires: libsasl2.so.3()(64bit) Error: Package: mysql-community-server-8.0.16-1.el7.x86_64 (mysql80-community) Requires: libstdc++.so.6(GLIBCXX_3.4.14)(64bit) Error: Package: mysql-community-server-8.0.16-1.el7.x86_64 (mysql80-community) Requires: libc.so.6(GLIBC_2.17)(64bit) Error: Package: mysql-community-server-8.0.16-1.el7.x86_64 (mysql80-community) Requires: libstdc++.so.6(GLIBCXX_3.4.15)(64bit) Error: Package: mysql-community-client-8.0.16-1.el7.x86_64 (mysql80-community) Requires: libstdc++.so.6(GLIBCXX_3.4.19)(64bit) Error: Package: mysql-community-client-8.0.16-1.el7.x86_64 (mysql80-community) Requires: libstdc++.so.6(CXXABI_1.3.5)(64bit) Error: Package: mysql-community-libs-8.0.16-1.el7.x86_64 (mysql80-community) Requires: libc.so.6(GLIBC_2.14)(64bit) Error: Package: mysql-community-server-8.0.16-1.el7.x86_64 (mysql80-community) Requires: libstdc++.so.6(GLIBCXX_3.4.17)(64bit) Error: Package: mysql-community-client-8.0.16-1.el7.x86_64 (mysql80-community) Requires: libstdc++.so.6(GLIBCXX_3.4.18)(64bit) You could try using --skip-broken to work around the problem ** Found 3 pre-existing rpmdb problem(s), 'yum check' output follows: 2:postfix-2.6.6-8.el6.x86_64 has missing requires of libmysqlclient.so.16()(64bit) 2:postfix-2.6.6-8.el6.x86_64 has missing requires of libmysqlclient.so.16(libmysqlclient_16)(64bit) 2:postfix-2.6.6-8.el6.x86_64 has missing requires of mysql-libs
麻烦写一下这个编程Stacks in C++
Lab Objectives. In this lab, you will practice what you had learned in Lecture 5 slides Description of the Problem: Stacks are used by compilers to help in the process of evaluating expressions and generating machine language code. In this exercise, we investigate how compilers evaluate arithm+c expressions consisting only of constants, operators and parenthese Humans generally write expressions like 3 + 4 and 7 / 9 in which the operator (+ or / here) is written between its operands—this is called infix notation. Computers “prefer” postfix notation in which the operator is written to the right of its two operands. The preceding infix expressions would appear in postfix notation as 3 4 + and 7 9 /, respectively. To evaluate a complex infix expression, a compiler would first convert the expression to postfix notation and evaluate the postfix version of the expression. Each of these algorithms requires only a single left-to-right pass of the expression. Each algorithm uses a stack object in support of its operation, and in each algorithm the stack is used for a different purpose. In this exercise, you will write a C++ version of the infix-to-postfix conversion algorithm using both the the LinkedStackBag and LinkedArrayBag from Part A. Please write a driver program that converts an ordinary infix arithmetic expression (assume a valid expression is entered) with single-digit integers such as (6 + 2) * 5 - 8 / 4 to a postfix expression. The postfix version of the preceding infix expression is 6 2 + 5 * 8 4 / - The program should read the expression into character array infix and use modified versions of the stack functions implemented in this chapter to help create the postfix expression in character array postfix. The algorithm for creating a postfix expression is as follows: * 1) Please push a left parenthesis '(' onto the stack. * 2) Please append a right parenthesis ')' to the end of infix. * 3) While the stack is not empty, please read infix from left to right and do the following: 1. If the current character in infix is a digit, please copy it to the next element of postfix. 1. If the current character in infix is a left parenthesis, please push it onto the stack. 1. If the current character in infix is an operator, 1. Please pop operators (if there are any) at the top of the stack while they have equal or higher precedence than the current operator, and please insert the popped operators in postfix. 1. Please push the current character in infix onto the stack. If the current character in infix is a right parenthesis Please pop operators from the top of the stack and insert them in postfix until a left parenthesis is at the top of the stack. Please pop (and discard) the left parenthesis from the stack. The following arithmetic operations are allowed in an expression: + addition - subtraction * multiplication * / division * ^ exponentiation * % modulus [Note: We assume left-to-right associativity for all operators for the purpose of this exercise.] The stack should be maintained with stack nodes, each containing a data member and a pointer to the next stack node. Some of the functional capabilities you may want to provide are: * a) function convertToPostfix that converts the infix expression to postfix notation * b) function isOperator that determines whether c is an operator * c) function precedence that determines whether the precedence of operator1 is less than, equal to or greater than the precedence of operator2 (the function returns –1, 0 and 1, respectively) * d) function push that pushes a value onto the stack * e) function pop that pops a value off the stack * f) function stackTop that returns the top value of the stack without popping the stack * g) function isEmpty that determines if the stack is empty * h) function printStack that prints the stack ================================================================================== .![图片说明](https://img-ask.csdn.net/upload/201910/27/1572151377_850711.png)
麻烦写一下这个程序,这是一个stacks in c++
Lab Objectives. In this lab, you will practice what you had learned in the Stack slides Description of the Problem: Please also include your UML design. You will use your StackArrayBag and LinkedArrayBag classes here. Please write a program that evaluates a postfix expression (assume it is valid) such as6 2 + 5 * 8 4 / - The program should read a postfix expression consisting of digits and operators into a character array. Using modified versions of the stack functions implemented earlier in this chapter, the program should scan the expression and evaluate it. The algorithm is as follows: * 1) Append the null character ('\0') to the end of the postfix expression. When the null character is encountered, no further processing is necessary. * 2) While '\0' has not been encountered, read the expression from left to right. If the current character is a digit, Push its integer value onto the stack (the integer value of a digit character is its value in the computer’s character set minus the value of '0' in the computer’s character set). Otherwise, if the current character is an operator, Pop the two top elements of the stack into variables x and y. Calculate y operator x. Push the result of the calculation onto the stack. * 3) When the null character is encountered in the expression, pop the top value of the stack. This is the result of the postfix expression. [Note: In Step 2 above, if the operator is '/', the top of the stack is 2 and the next element in the stack is 8, then pop 2 into x, pop 8 into y, evaluate 8 / 2 and push the result, 4, back onto the stack. This note also applies to operator '–'.] The arithmetic operations allowed in an expression are + addition – subtraction * multiplication * / division * ^ exponentiation * % modulus [Note: We assume left-to-right associativity for all operators for the purpose of this exercise.] The stack should be maintained with stack nodes that contain an int data member and a pointer to the next stack node. You may want to provide the following functional capabilities: a) function evaluatePostfixExpression that evaluates the postfix expression b) function calculate that evaluates the expression op1 operator op2 c) function push that pushes a value onto the stack d) function pop that pops a value off the stack e) function isEmpty that determines if the stack is empty f) function printStack that prints the stack ![图片说明](https://img-ask.csdn.net/upload/201910/27/1572151878_677756.png)
130 个相见恨晚的超实用网站,一次性分享出来
相见恨晚的超实用网站 持续更新中。。。
我花了一夜用数据结构给女朋友写个H5走迷宫游戏
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《奇巧淫技》系列-python!!每天早上八点自动发送天气预报邮件到QQ邮箱
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致 Python 初学者
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致 Python 初学者们!
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究竟你适不适合买Mac?
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使用 Angular 打造微前端架构的 ToB 企业级应用
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大学四年因为知道了这32个网站,我成了别人眼中的大神!
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深度学习笔记------卷积神经网络
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普通三本毕业,我怎么一路艰辛进入阿里的
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