strcpy能否影响strcmp结果的c语言？

Question

编辑：更改标题以反映帖子中的两种方法。

我正在尝试比较c语言中的两个字符串，但由于某种原因，它始终打印两个字符串不相等

#include <stdio.h>
#include <string.h>


int main()
{
    /* A nice long string */

    char test[30]="hellow world";

    char test2[30];

    // to copy string from first array to second array

    strcpy(test2, test);



    /* now comparing two stering*/

    if(strcmp(test2, test))
       printf("strigs are equal  ");
    else

    printf("not equal  \n");

    printf("value of first string  is %s and second string is %s",test,test2);
    printf("length of string1 is %zu and other string is %zu ",strlen(test2),strlen(test2));



}

我总是得到输出

not equal  
value of first string  is hellow world and second string is hellow worldlength of string1 is 12 and other string is 12 

Answer 1

你的问题在于你如何使用strcmp 。 当字符串相等时， strcmp返回0（其值为false）（当字符串为“按顺序”时返回正数，当它们“乱序”时返回负数）。

Answer 2

当两个字符串相同时， strcmp返回0，而在C中，0的计算结果为false。尝试：

if(strcmp(test2, test)==0)

Answer 3

根据C ++引用Return value of strcmp -A zero value indicates that both strings are equal. -A value greater than zero indicates that the first character that does not match has a greater value in str1 than in str2; And a value less than zero indicates the opposite. Return value of strcmp -A zero value indicates that both strings are equal. -A value greater than zero indicates that the first character that does not match has a greater value in str1 than in str2; And a value less than zero indicates the opposite.

将你的条件改为if(!strcmp(test2, test)) ，它应该有效。

Answer 4

如果字符串相等，strcmp（）返回0。 例如， 参见http://www.cplusplus.com/reference/clibrary/cstring/strcmp/

Answer 5

strcmp()在相等时返回0

Answer 6

如果给定的两个字符串相等，则strcmp返回0。

我还修复了一些拼写错误，在最后一个printf()你已经两次调用了strlen(test2) ！ - 纠正这一点

#include <stdio.h>
#include <string.h>

int main()
{
    /* A nice long string */

    char test[30]="hello world";

    char test2[30];

    // to copy string from first array to second array

    strcpy(test2, test);

    /* now comparing two stering*/

    if(!strcmp(test2, test))
        printf("strigs are equal \n");
    else
        printf("not equal  \n");

    printf("value of first string is %s \nsecond string is %s \n", test, test2);
    printf("length of string1 is %zu \nsecond string is %zu \n",strlen(test), strlen(test2));

    return 0;
}

输出：

$ ./a.out 
strigs are equal 
value of first string is hello world 
second string is hello world 
length of string1 is 11 
second string is 11 
$ 

Answer 7

man strcmp：“strcmp（）函数比较两个字符串s1和s2。如果找到s1，则返回小于，等于或大于零的整数，小于，匹配或大于S2“。