condense.c

/* I'm a C++ programmer by day, so when I saw this problem, I thought it would
 * be worthwhile to hack it up. I changed the variable names to help me think
 * about the problem, not for some kind of obfuscation. I'm curious how my
 * solution compares to solutions devised by C programmers. */

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

void condense_by_removing(char *s, char rm) {
        /* Assume `s` is a null-terminated string. */
        char *s1 = s;
        char *s2 = s;

        /* No sense in continuing if \0 is to be removed or s is null. */
        if(rm == 0 || s == 0) return;

        while(*s2) {
                if(*s2 == rm) ++s2;
                else *s1++ = *s2++;
        }
        *s1 = '\0';
}

const size_t MAX_BUF = 1024*1024*sizeof(char);
int main(int argc, char **argv) {
        char* str;

        if(argc < 2) return EXIT_FAILURE;

        str = malloc(MAX_BUF);
        if(!str) return EXIT_FAILURE;

        while(fgets(str, MAX_BUF, stdin)) {
                condense_by_removing(str, argv[1][0]);
                printf("%s", str);
        }
        return EXIT_SUCCESS;
}