how to remove extra spaces from string in C

Question

I have an string that have an extra spaces string, for example:

char * s = "  foo    baa       ";

I want to conver it to:

foo baa

I have wrote this function:

void trim (char ** src)
    {
        char * p = strdup(* src);
        char * ret = malloc(strlen(*src) + 1);
                assert(ret != NULL);
        char * token;
        token = strtok(p, " \t");
        while( NULL != token ) {
            while (*token) {
                 *(ret ++) = *(token ++);
            }
            token = strtok(NULL, " \t");
        }

        printf("ret = %s\n", ret);
    }

but it given for me an empty string from ret variable value. someone may point out my mistake? thanks in advance.

Answer 1

You are incrementing ret in your while, store the original address or use subscript to access different chars of ret .

    // snip
    char * ret = malloc(strlen(*src) + 1);
            assert(ret != NULL);
    char * ret_start = ret;
    //snap
    printf("ret_start = %s\n", ret_start);

Answer 2

Other naive solution in c++(can be easily changed to c code )----- :)

initially count=0 and str -> your c++ string

for(i=0;i< str.size();i++)
{
        if(str[i]!=' ')
        {
                str[j++]=str[i];
                count=0;
        }
        else if(str[i]==' '&&count==0)
        {
                str[j++]=str[i];
                count =1;
        }
}