Strcmp（）函数未返回0

Question

i was trying to compare two strings using strcmp() , and in the case they're equal the function returns -1 (meaning they are not equal) , i dont know whats wrong .

int main()
{
char password[]={'6','6','6','6','6','6'};
char passmatch[6];
int i =0;
for(i ; i<6 ; i++)
{
    passmatch[i]='6';
}

printf("\n");
if(strcmp(password,passmatch)==0)
{
    printf("Strings are equal");
}
else
{
    printf("String are'nt equal");
}


return 0;

}

Answer 1

In C, strings need to be null terminated in order to be used with the standard library. Try putting a '\\0' at the end, or make a string literal in the "normal" way, eg char password[] = "666666"; , then the language will automatically put \\0 at the end.

Answer 2

The problem is that in C '6' (with quotes) is not the same as 6 (without quotes). That's why this loop

for(i ; i<6 ; i++) {
    passmatch[i]=6; // <<== Should be '6', not 6
}

is not assigning what you want it to assign. If you put quotes around this 6 as well, you would get the right content, but your program would remain broken, because strcmp requires null termination.

You can fix it in two ways:

• Add null termination to both C strings, either manually or by initializing with a string literal,
• Switch to using memcmp , which takes length, and therefore does not require null termination.