找错：字符串输出字母数字，不要下划线

Question

输入字符串后，要求程序输出字符串中数字字母，其余删除。
#include<stdio.h>
int main()
{
char c1[100] = { '\0' };
char c2[100] = { '\0' };
int i=0;
printf("请输入字符串\n");
gets(c1);
while(c1[i]!='\0')
{
if ((c1[i] > 48 && c1[i] < 57) || (c1[i] > 'a' && c2[i] < 'z') || (c1[i] > 'A' && c2[i] < 'Z'))
{
c2[i] = c1[i];
}
i++;
}
i = 0;
while(c2[i]!='\0')
{
printf("%c", c2[i]);
i++;
}
}

Answer 1

哈喽，具体修改代码如下，有用请点采纳哦~

#include<stdio.h>
int main()
{
    char c1[100] = { '\0' };
    int i=0;
    printf("请输入字符串\n");
    gets(c1);
    while(c1[i]!='\0')
    {
        if ((c1[i] >= '0' && c1[i] <= '9') || (c1[i] >= 'a' && c1[i] <= 'z') || (c1[i] >= 'A' && c1[i] <= 'Z'))
        {
            printf("%c", c1[i]);
        }
        i++;
        
    }
}