string-whitespace

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


char* whitespace (char* s) {
    int i=0,j=0;
    char *poc=s;
    while (*(s+i)!='\0') {
            if(*(s+i)==' ' || *(s+i)=='\t' || *(s+i)=='\n')
               { *(s+i)=' ';
                 j=i+1;
                 while (*(s+j)==' ' || *(s+j)=='\t' || *(s+j)=='\n') j++;
                 if (j!=i+1) {
                        while (*(s+1+i)!='\0') {
                                *(s+i+1)=*(s+j);
                                s++;
                        }
                        *(s+i)='\0';
                 } s=poc;
               }
               i++;
    }

    return poc;
    }

int main () {
    printf("Unesite jednu recenicu sa maks. 100 znakova: ");
    char recenica[100],c;
    int i=0,n;
    do {
            c=getchar();
            recenica[i]=c;
            i++;
    } while (c!='\n' && i<100);
    recenica[i-1]='\0';

    printf("\nNova recenica glasi: %s",whitespace(recenica));
    return 0;
}