Better Way Without Goto? - c

Question

I have a program where my code uses a goto statement, and I want to get rid of it in a nice way, but I can't seem to find a solution. If goto is the best way, then please let me know. Here is a summary of the code:
//Counts how many times every word appears in a file
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define NUMWORDS 1000
#define WORDLEN 50
typedef struct
{
char word[WORDLEN + 1];
int num;
} Appearance;
int main(int argc, char *argv[]) {
FILE *readfile;
Appearance *appearlist[NUMWORDS] = {NULL};
char word[WORDLEN + 1];
int i;
//Get a valid filename and open the file, store pointer into readfile
...
char c;
while (c != EOF) {
skip: //Annoying label
//Get a word from readfile, store into word
...
if (word[0] != '\0') {
for (i = 0; i < NUMWORDS && appearlist[i]; i++) {
if (strcmp(appearlist[i] -> word, word) == 0) {
appearlist[i] -> num++;
goto skip; //Annoying goto
}
}
appearlist[i] = (Appearance *) malloc(sizeof(Appearance));
appearlist[i] -> num = 1;
strcpy(appearlist[i] -> word, word);
}
}
//Display results, free memory
...
return 0;
}
The problem is, I want to skip code that is outside of the loop I want to skip from. I would like to not create another variable only designed for this. If you want the full code, click on "Show code snippet."
//Counts how many times every word appears in a file
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define NUMWORDS 1000
#define WORDLEN 50
#define FILENAMELEN 50
typedef struct
{
char word[WORDLEN + 1];
int num;
} Appearance;
int main(int argc, char *argv[])
{
char filename[FILENAMELEN];
FILE *readfile;
Appearance *appearlist[NUMWORDS] = {NULL};
char word[WORDLEN + 1];
size_t ln;
int i;
if (argc == 2)
strncpy(filename, argv[1], sizeof(filename));
else {
printf("Enter a filename to count appearances from, or just press enter to quit: ");
fgets(filename, FILENAMELEN, stdin);
ln = strlen(filename) - 1;
if (filename[ln] == '\n')
filename[ln] = '\0';
}
while((readfile = fopen(filename, "r")) == NULL) {
if (filename[0] == '\0')
return 0;
printf("Invalid file! Please enter another filename, or just press enter to quit: ");
fgets(filename, FILENAMELEN, stdin);
ln = strlen(filename) - 1;
if (filename[ln] == '\n') filename[ln] = '\0';
}
char c;
while (c != EOF) {
skip:
for (i = 0; (c = getc(readfile)) != EOF && (isalnum(c) || c == '\''); i++) {
if (i >= WORDLEN) {
word[i] = '\0';
printf("\nWarning: word too long (over %d characters), trimming to: %s\n", WORDLEN, word);
while ((c = getc(readfile)) != EOF && (isalnum(c) || c == '\'')) ;
} else {
word[i] = tolower(c);
}
}
word[i] = '\0';
if (word[0] != '\0') {
for (i = 0; i < NUMWORDS && appearlist[i]; i++) {
if (strcmp(appearlist[i] -> word, word) == 0) {
appearlist[i] -> num++;
goto skip;
}
}
appearlist[i] = (Appearance *) malloc(sizeof(Appearance));
appearlist[i] -> num = 1;
strcpy(appearlist[i] -> word, word);
}
}
for (i = 0; i < NUMWORDS && appearlist[i]; i++) {
printf("Word: %s, Appearances: %d\n", appearlist[i] -> word, appearlist[i] -> num);
free(appearlist[i]);
}
return 0;
}

Answer 1

Using goto in this case is often considered acceptable.
Alternatives would be to set a variable so that you can continue in the outer loop after breaking from the inner one, or turning the whole segment that you want to escape from into a separate function, and returning from it instead of using goto.
I'm ignoring any other issues there may be with the code that aren't relevant to the question!

Answer 2

Put everything beginning with the 'if' statement into a separate method (let's call it "process" and replace the goto with return. Then the while-loop becomes:
while (c != EOF) {
//Get a word from readfile, store into word
...
process(...);
}

Answer 3

Sometimes using goto is a hint that code should use a helper function
static bool findword(Appearance *appearlist, size_t size, const char *word) {
for (size_t i = 0; i < size && appearlist[i]; i++) {
if (strcmp(appearlist[i]->word, word) == 0) {
appearlist[i]->num++;
return true;
}
}
return false;
}
while (c != EOF) {
//Get a word from readfile, store into word
...
if (word[0] != '\0') {
if (findword(appearlist, NUMWORDS, word)) {
continue;
}
appearlist[i] = (Appearance *) malloc(sizeof(Appearance));
appearlist[i] -> num = 1;
strcpy(appearlist[i] -> word, word);
}
}