strcpy能否影響strcmp結果的c語言？

Question

編輯：更改標題以反映帖子中的兩種方法。

我正在嘗試比較c語言中的兩個字符串，但由於某種原因，它始終打印兩個字符串不相等

#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));



}

我總是得到輸出

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

你的問題在於你如何使用strcmp 。 當字符串相等時， strcmp返回0（其值為false）（當字符串為“按順序”時返回正數，當它們“亂序”時返回負數）。

Answer 2

當兩個字符串相同時， strcmp返回0，而在C中，0的計算結果為false。嘗試：

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

Answer 3

根據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.

將你的條件改為if(!strcmp(test2, test)) ，它應該有效。

Answer 4

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

Answer 5

strcmp()在相等時返回0

Answer 6

如果給定的兩個字符串相等，則strcmp返回0。

我還修復了一些拼寫錯誤，在最后一個printf()你已經兩次調用了strlen(test2) ！ - 糾正這一點

#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;
}

輸出：

$ ./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（）函數比較兩個字符串s1和s2。如果找到s1，則返回小於，等於或大於零的整數，小於，匹配或大於S2“。