diff --git a/CppCoreGuidelines.md b/CppCoreGuidelines.md index c05d8ee..ca50e0c 100644 --- a/CppCoreGuidelines.md +++ b/CppCoreGuidelines.md @@ -7222,21 +7222,26 @@ This will copy each elements of `vs` into `s`. Better ### ES.74: Prefer to declare a loop variable in the initializer part of as `for`-statement -**Reason**: 1) By creating variables inside loops, you ensure their scope is restricted to inside the loop. It - cannot be referenced nor called outside of the loop. - 2) some dedicated optimization can be performed more efficiently by the compiler (most importantly - register allocation), since it knows that the variable cannot be used outside of the loop. For - example, no need to store the result for later re-use. +**Reason**: Limit the loop variable visibility to the scope of the loop. +Avoid using the loop variable for other purposes after the loop. **Example**: - for (int counter = 0; counter <= 10; counter++) - { - cout << counter << endl ; - } + for (int i=0; i<100; ++i) { // GOOD: i var is visible only inside the loop + // ... + } -**Enforcement**: ??? +**Example; don't**: + int j; // BAD: j is visible outside the loop + for (j=0; j<100; ++j) { + // ... + } + // j is still visible here and isn't needed + +**See also**: [Don't use a variable for two unrelated purposes](#Res-recycle) + +**Enforcement**: Warn when a variable modified inside the `for`-statement is declared outside the loop and not being used outside the loop. ### ES.75: Avoid `do`-statements