c - 为什么看起来字符串不相等？

Question

int main()
{        
    int n = 100;    
    char a[n];    
    char b[ ]="house";

    fgets(a,n-1,stdin); // type "house"

    if (strcmp(a,b) == 0)
        printf("The strings are equal.\n");
    else
        printf("The strings are not equal.\n");

    return 0;
}

Answer 1

这是为什么

if (strcmp(a,b) == 0) { }

不正确，因为 fgets() 将 \n 存储在缓冲区的末尾。所以这里的数组 a 看起来像 house 而数组 b 看起来像 house\n(如果 ENTER 键在输入字符后被按下)并且 strcmp(a,b) 不返回 0。 来自 fgets()

的手册页

fgets() reads in at most one less than size characters from stream and stores them into the buffer pointed to by s. Reading stops after an EOF or a newline. If a newline is read, it is stored into the buffer. A terminating null byte ('\0') is stored after the last character in the buffer.

一种方法是使用 strcspn() 删除尾随的 \n。例如

fgets(a,n,stdin);
a[strcspn(a, "\n")] = 0;

现在比较一下char数组

if (strcmp(a,b) == 0) {
        printf("The strings are equal.\n");
}
else {
        printf("The strings are not equal.\n");
}