简单的C程序returns无输出

Question

我写了一个简单的 C 程序，它接受用户输入并将其存储在 dataofUser 变量中，然后它允许用户通过说是或否来选择是否要显示他们输入的数据，这是通过 fgets 完成的和一个 if 语句，它检查 userChoice 变量是否在其中存储了是或否取决于它是或否它将显示数据或显示 "no output!"，当我运行程序时我没有输出我在下面输入的数据中，您可以看到控制台上显示的内容：

Please enter your input: this is a random input
Your data has been entered please enter Yes or No to display it: yes

Process returned 0 (0x0)    execution time : 4.829 s
Press ENTER to continue.

这是构建消息日志和各种错误消息

||=== Build: Debug in randopoint2 (compiler: GNU GCC Compiler) ===|
/home/Documents/randopoint2/randopoint2/main.c||In function ‘main’:|
/home/Documents/randopoint2/randopoint2/main.c|17|warning: comparison between pointer and integer|
/home/Documents/randopoint2/randopoint2/main.c|17|warning: comparison with string literal results in unspecified behavior [-Waddress]|
/home/Documents/randopoint2/randopoint2/main.c|21|warning: comparison between pointer and integer|
/home/Documents/randopoint2/randopoint2/main.c|21|warning: comparison with string literal results in unspecified behavior [-Waddress]|
||=== Build finished: 0 error(s), 4 warning(s) (0 minute(s), 0 second(s)) ===|
||=== Run: Debug in randopoint2 (compiler: GNU GCC Compiler) ===|

#include <stdio.h>
#include <stdlib.h>

int main()
{
    char dataOfUser[50];
   char userChoice[50];

  printf("Please enter your input: ");
  fgets(dataOfUser, 50, stdin);

  printf("Your data has been entered please enter Yes or No to dipslay it: ");
  fgets(userChoice, 50, stdin);


  if(userChoice[50] == "yes")
  {
  printf("Your notes are: %s", dataOfUser);
  }
  else if(userChoice[50] == "no")
  {
  printf("no output!");
  }

    return 0;
}

Answer 1

问题：

if(userChoice[50] == "yes")

在 C 语言中，这不是比较字符串的方式。

此外，访问 userChoice[50] 是未定义的行为，因为您正试图越界访问数组。

else if(userChoice[50] == "no")

也一样

另请注意，当您按回车键结束输入时，换行符 \n 存储在 userChoice.

解法：

添加#include <string.h>得到strcmp函数。
将if(userChoice[50] == "yes")改为if (strcmp(userChoice, "yes\n") == 0)
将else if(userChoice[50] == "no")更改为else if (strcmp(userChoice, "no\n") == 0)

旁白：

printf("Your data has been entered please enter Yes or No to dipslay it: ");

您要求用户输入 "Yes" 或 "No"，但将其与代码中的 "yes" 和 "no" 进行比较。

简单的C程序returns无输出

Simple C program returns no output

c

pointers

fgets

strcmp