Using C++ STL functions instead of loops – EasyHack

By Hossein Nourikhah On 11 September 2025 In Uncategorised

C++ Standard library, which resides in std:: namespace provides common classes and functions which can be used by developers. Among them, Standard Template Library (STL) provides classes and functions to better manage data through data structures named containers. Here I discuss how to use STL functions for better processing of data, and avoid loops.

Checking Conditions

To iterate over a container to see if some specific condition is valid for all, any, or none of the elements in that container, C/C++ developers traditionally used loops.

On the other hand, since C++11, there are functions that can handle such cases: all_of, any_of and none_of. These functions process STL containers, and can replace loops. If you want to know if a function returns true for all, any, or none of the items of the container, then you can simply use these functions. This is the EasyHack dedicated to such a change:

153109 – Use all_of, any_of or none_of from STD instead of looping to check a condition over a range

Here is an example patch which uses any_of instead of a loop:

-    bool bFound = false;
     // convert ASCII apostrophe to the typographic one
     const OUString aText( rOrig.indexOf( '\'' ) > -1 ? rOrig.replace('\'', u'’') : rOrig );
-    size_t nCnt = aVec.size();
-    for (size_t i = 0;  !bFound && i < nCnt;  ++i)
-    {
-        if (aVec[i] == aText)
-            bFound = true;
-    }
+    const bool bFound = std::any_of(aVec.begin(), aVec.end(),
+        [&aText](const OUString& n){ return n == aText; });

As you can see, the new code is more concise, and avoids using loops.

Conditional Copying, Removing and Finding

If you want to copy, remove or simply find a value in a container which conforms to a specific functions, you may use copy_if, remove_if or find_if.

153294 – Use copy_if, find_if or remove_if to simplify loops

Again, this is an example patch:

-  for ( size_t i = 0; i < SAL_N_ELEMENTS( arrOEMCP ); ++i )
-        if ( arrOEMCP[i] == codepage )
-            return true;
-
-    return false;
+    return std::find(std::begin(arrOEMCP), std::end(arrOEMCP), codepage) != std::end(arrOEMCP);