CODEWITHSUNDEEP
c++c
studinstru
studinstru

Reputation: 124

Get rid of goto statement from embedded C/C++ logic

I want to get rid of this goto statement. Can any one tell me the logic for the same. The code below is not the exact code that I want to modify, but it will support my question. Please don't ask the significance of the code when commenting on this post as it is just an example.

int result[i][j];
for (int i = 0; i<100; i++)
{
    for (j = 0; j<100; j++)
    {
        result[i][j] = j++;
        if (j == 80)
            goto break1;
    }
}
break1:
…;

Upvotes: 4

Views: 1546

Answers (7)

EvilTeach
EvilTeach

Reputation: 28837

int result[i][j];
for (int i = 0; i<100; i++)
{
    for (j = 0; j<100; j++)
    {
        result[i][j] = j++;
        if (j == 80)
        {
           i = 100;
           break;
        }
    }
}

The break statement breaks out of the inner loop. Setting i to 100, causes the outer loop to finish.

Upvotes: 0

Levi Riley
Levi Riley

Reputation: 1

int result[i][j];
for (int i = 0; i<100; i++)
{
    int j;
    for (j = 0; j<100; j++)
    {
        result[i][j] = j++;
        if (j == 80)break;
    }
    if(j == 80) break;
}

Know this is an old question but can be modified simply

Upvotes: 0

Michel Keijzers
Michel Keijzers

Reputation: 15357

Use a boolean to break from the for loop(s).

int result[i][j];
bool cont = 1;
for (int i =0;i<100;i++)
{
    for(j = 0;j<100;j++)
    {
        result[i][j] = j++;
        if(j == 80)
        {
            cont = 0;            
            break; 
        }
    }
    if (cont == 0)
        break;
}
break1;

(note: not tested on real compiler).

Upvotes: 1

Baum mit Augen
Baum mit Augen

Reputation: 50053

Put those loops in a function, give it a proper name and return; when it is done. If it is complicated enough to need two loops, it deserves a name.

A finished flag is so hard to read that you should put that construct in its own function anyway, making it obsolete.

Exceptions are only for errors you cannot handle locally. Use them to notify higher level functions that something you cannot fix went wrong, not if something that was supposed to happen happened.

Upvotes: 4

pmg
pmg

Reputation: 108978

I sometimes like changing the control variable(s)

for (int i = 0; i < 100; i++) {
    for (int j = 0; j < 100; j++) {
        /* work */
        if (j == 80) i = j = 100; // 100 makes both loops terminate
    }
}

Upvotes: 0

Philipp
Philipp

Reputation: 69663

I would see three possible solutions.

  1. Put the code into a function and leave that function with return
  2. Use a "finished" flag like already demonstrated well in the answers by Michel Keijzers, Bas in het Feld and EvilTeach.
  3. (C++ only) surround the code-section with a try-catch-block and throw and exception when you want to leave the code. But keep in mind that exceptions are usually supposed to be used for error-handling. So you should only use this pattern when terminating the loops is the result of an error conditions.

Upvotes: 2

Bas in het Veld
Bas in het Veld

Reputation: 1312

Since you want to break two loops, you have to notify the outer loop. You can do this by having a boolean that checks for that:

bool break_loop = false;
for (int i = 0; i < 100; ++i) {
    for (int j = 0; j < 100; ++j) {
        if (j == 80) {
            break_loop = true;
            break;
        }
    }
    if (break_loop) break;
}

Upvotes: 1

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