c语言 文件程序设计 跪求谢谢大佬来解答

Question

假设文件address.txt中已存放3位联系人信息，编写程序，从键盘输入1位联系人信息，序号：4，姓名：小鹿，性别：女，电话号码：[phone]，把该联系人添加到文件里。然后从文件中读出全部信息，并在屏幕上显示。

Answer 1

你将就着用吧, 忘记怎么格式化写入了,就用了笨办法
int main()
{

FILE *fp = NULL;

if (fopen_s(&fp, "address.txt","a+")!=0) //open the file by write
{
    printf_s("error");
    return -1;
}
else
{
    char tempInfo[20];
    printf_s("please input the cantact's index:\n");
    scanf_s("%s", tempInfo,sizeof(tempInfo));
    fputs("\n", fp);
    fputs(tempInfo,fp);
    printf_s("please input the cantact's name:\n");
    scanf_s("%s", tempInfo, sizeof(tempInfo));
    fputs(tempInfo, fp);
    fputs("   ", fp);
    printf_s("please input the cantact's sex:\n");
    scanf_s("%s", tempInfo, sizeof(tempInfo));
    fputs(tempInfo, fp);
    fputs("   ", fp);
    printf_s("please input the cantact'TEL:\n");
    scanf_s("%s", tempInfo, sizeof(tempInfo));
    fputs(tempInfo, fp);
    fputs("   ", fp);

}
fclose(fp);
char StrLine[1024];
fopen_s(&fp, "address.txt","r");  //open the file by read
while (!feof(fp))
{
    fgets(StrLine, 1024, fp);
    printf_s("%s", StrLine);
}
fclose(fp);
return 0;

}