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Home » Tip Bank » C++
Language: C++
Expertise: Beginner
Apr 5, 2002



Building the Right Environment to Support AI, Machine Learning and Deep Learning

Avoid Nesting Errors

There are two very annoying--yet completely avoidable--nesting errors that occur in C/C++ programming.

1) This one typically happens toward the end of the day, thereby making the day longer:
for (int i=0; i < 10; i++);
    // Statements
After a long day, seeing the notorious ";{" error can be frustrating, even if is it is inside of a small module. The fix is to put the "{" on the same line as the "for": for (int i=0; i < 10; i++) { // Statements }
Since having these two together is very noticeable, this can help you avoid the errors. With good reason, this style is used in the Java style guide.

The other common nesting error regards single statements and occurs during code maintenance. Consider this code snippet:
for (int i=0; i < 10; i++)
    cout << "i=" << i << endl;

Later, someone decides to add functionality to this loop:
for (int i=0; i < 10; i++)
    cout << "i=" << i << endl;
    cout << "i^2=" << i*i << endl;

Of course, the braces are missing. The maintainable approach is to always use braces. This prevents the error and does not increase execution time:
for (int i=0; i < 10; i++) {
    cout << "i=" << i << endl;

Less acceptable is the single line:
for (int i=0; i < 10; i++) cout << "i=" << i << endl;

This requires the addition of {} and a new line when statements are added.

The "brace on the next line" style has its roots in Pascal programming where it is far easier to see a missing BEGIN/END than a lowly semicolon.

Although some programmers regard the same-line-brace vs. next-line-brace as a religious matter, I strongly recommend it as a bug-avoiding style.
Dale Shpak
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