tolower() not working

问题

The below code snippet is used to convert a string to lower case.

int main()
{
    unsigned char s[] = "AbS.d_";

    tolower(s);
    printf("%s\n", s);

    return 0;
}

I am getting the output as:

AbS.d_

Why the string is not being converted?

回答1:

tolower takes int and return lowered int.

This should work:

int i=0;
for(i=0; s[i]; i++)
{
    s[i]=tolower(s[i]);
}

回答2:

tolower takes a character type as parameter, but you use a string. You need to run through your array, and call tolower for each character.

来源：https://stackoverflow.com/questions/12145463/tolower-not-working