How to use for each loop in c++

Question

#include <cstdlib>
#include <iostream>
#include <string>
using namespace std;
int main() {
    string str("hello world!");
    for (auto &c : str)
        c = toupper(c);
    cout << str;
    return 0;
}

This c++ code does not compile. Error msg: main.cpp:21: error: a function-definition is not allowed here before ':' token Question: Is there a for each loop in c++ (range for loop?)? what is wrong with the for each loop above?

Thanks in advance.

Solution 1

The code is valid, as can be demonstrated on an online compiler.

Please refer to your compiler documentation to be sure you have enabled C++11. The option is often called -std=c++11. You might have to download an upgrade; check your package manager for GCC (currently at 4.8) or Clang (currently 3.3).

Solution 2

Prior to C++11x, for_each is defined in the algorithm header. Simply use:

for_each (vec.begin(), vec.end(), fn);

where fn is a function to which the element will be passed, and the first two arguments are input iterators.

Also, after including both string and algorithm you could just use

std::transform(str.begin(), str.end(),str.begin(), ::toupper);

Comments

[jogojapan]

It exists in C++11. Make sure you use a compiler that can handle C++11, and make sure you enable the required options for that.

[jogojapan]

std::for_each is still defined in the algorithm header, even in C++11. (The range-based for-loop introduced by C++11 into the language core has not replaced the std::for_each algorithm, even though there is some overlap in the use cases.)