WTF Ruin a band name by changing one letter

@Jehannum
Code:
#include <stdio.h>
#include <string.h>

int diffchars(char *a, char *b, int wordlen);

int main(int argc, char **argv) {
  
    if (argc != 3) {
        fprintf(stderr,"usage: %s <wordlist.txt> <word>\n",argv[0]);
        return 0;
        }
  
    FILE *f = fopen(argv[1],"r");
    if (f == NULL) {
        fprintf(stderr,"Could not open wordlist file \"%s\"\n",argv[2]);
        return 0;
    }
  
    int wordlen = strlen(argv[2]);
    char line[50];
  
    while(!feof(f)) {
        if (fgets(line,50,f) == NULL) break;
        line[strcspn(line, "\n")] = 0;        // remove null terminator
        if (strlen(line) != wordlen) continue;
        if (diffchars(argv[2],line,wordlen) == 1) {
            fprintf(stdout,"%s\n",line);
        }
    }
  
    fclose(f);
    return 1;
}

int diffchars(char *a, char *b, int wordlen) {
    int diffs = 0;
  
    while(wordlen--)
        if (*a++ != *b++) diffs++;
    return diffs;
}

hmm, lets try Tom Petty...
Code:
gmarsh@torrentbox:~/c$ ./wordfind scrabble.txt petty
jetty
netty
patty
peaty
pesty
petti
petto
potty
putty
gmarsh@torrentbox:~/c$

Tom Potty it is!
Lol C to write a string manipulation algorithm?

Is C the only language you know?