Undeclared identifier when printing inside a for loop, although it seems the identifier is clearly stated

Question

When printing a variable inside a loop I get an error message about a undeclared identifier. The variable that gives the error is "j".

// Record preference if vote is valid
bool vote(int voter, int rank, string name)
{
    for (int i = 0; i < candidate_count; i++)
    {
    if (strcmp(candidates[i].name, name)==0)
    {
        for(int j = 1; j <candidate_count; j++)
        preferences[i][j] = rank;
        printf("i = (%i) j = (%i)\n", i , j);
        printf("prefenrences[i][j], (%i)(%i)\n", preferences[i][j]);


        return true;
    }
    }
    printf("text");
    return false;
}

The error message I get is as followed:

" runoff.c:137:43: error: use of undeclared identifier 'j' printf("i = (%i) j = (%i)\n", i , j); ^ fatal error: too many errors emitted, stopping now [-ferror-limit=] 2 errors generated. make: *** [: runoff] Error 1 "

I tried to rename the variable, or switch it to see what the problem is. I'm doing CS50 which is an introductional course to programming, so I'm not too sure what to do at this point. All help is appreciciated.

If you used less erratic indentation, you'd realize that only `preferences[i][j] = rank;` is the body of the `for (int j - 1; …)` loop. You need to use braces around the two `printf()` statements (and the assignment) to group them into the loop body. — Jonathan Leffler, Oct 31 '22 at 04:29
I see my mistake. One of the aspects of CS50 is style, and I'll definitely pay more attention to it now. Thank you for your help, my code works now! — Neuquert, Oct 31 '22 at 04:33
Apologies for the typos in the initial comment. My answer contains a more accurate version of that comment. — Jonathan Leffler, Oct 31 '22 at 04:36

Jonathan Leffler · Accepted Answer · 2022-10-31T13:07:40.740

If you used less erratic indentation, you'd realize that only preferences[i][j] = rank; is in the body of the for (int j = 1; …) loop. You need to use braces around at least the two printf() statements (and the assignment) to group them into the loop body; the loop body should probably include the return statement too.

You have:

bool vote(int voter, int rank, string name)
{
    for (int i = 0; i < candidate_count; i++)
    {
        if (strcmp(candidates[i].name, name)==0)
        {
            for (int j = 1; j <candidate_count; j++)
                preferences[i][j] = rank;
            printf("i = (%i) j = (%i)\n", i , j);
            printf("prefenrences[i][j], (%i)(%i)\n", preferences[i][j]);
            return true;
        }
    }
    printf("text");
    return false;
}

You probably need:

bool vote(int voter, int rank, string name)
{
    for (int i = 0; i < candidate_count; i++)
    {
        if (strcmp(candidates[i].name, name) == 0)
        {
            for (int j = 1; j < candidate_count; j++)
            {
                preferences[i][j] = rank;
                printf("i = (%i) j = (%i)\n", i , j);
                printf("prefenrences[i][j], (%i)\n", preferences[i][j]);
                return true;
            }
        }
    }
    printf("text\n");
    return false;
}

Note that I've corrected the second printf() so that there is only one %i conversion specification since you only pass one value to be formatted.

Undeclared identifier when printing inside a for loop, although it seems the identifier is clearly stated

1 Answers1