Question

I am trying to write a code to remove all the leading, trailing and middle of the sentence spaces but to keep only one space between the words.

For example if the input is

"    This    is my     string    "

the output should be

"This is my string"

So far I have come up with this:

#include <stdio.h>
void cascade(char str[], int i);
main()
{
    char str[100] = "    This    is my     string    ";
    int i = 0;
    while (str[i] != '\0') {
            if (str[i] == ' ' && str[i + 1] == ' ')
                    cascade(str, i);
            i++;
    }
    printf("%s\n", str);
}

void cascade(char str[], int i)
{
    while(str[i] != '\0') {
            str[i] = str[i + 1];
            i++;
    }
    str[i + 1] = '\0';
}

I would appreciate if anyone could come up with some ideas, Thank you.

Answer 1

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

char* trim(char str[]){
    char *p=str;
    char *token;
    if(str == NULL) return NULL;
    if(*str == '\0') return str;

    token=strtok(str, " \t");
    if(token == NULL){
        *str = '\0';
        return str;
    }
    while(NULL!=token){
        int len;
        len = strlen(token);
        if(p != token){
            memmove(p, token, len);
        }
        p += len;
        *p++ =' ';
        token = strtok(NULL, " \t");
    }
    p[-1]='\0';

    return str;
}

int main(){
    char str[100] = "    This    is my     string    ";
    printf("\"%s\"\n", trim(str));
    return 0;
}