Problem

I saw an example for range-based for loop in a Stack Overflow question and I compiled it in my own computer.¹ Then I got an error.

$ g++ temp1.cpp
temp1.cpp: In function ‘int main()’:
temp1.cpp:9:18: error: range-based ‘for’ loops are not allowed in C++98 mode
    for (int i : bar) {
                  ^
temp1.cpp: In function ‘void foo(int (&)[3])’:
temp1.cpp:16:18: error: range-based ‘for’ loops are not allowed in C++98 mode
    for (int i : bar) {
                  ^

I also received similar message after I typed the command for compiling the program with clang++.

Solution

I searched “gcc range based for loop are not allowed in” on Google, and realised that I forgot to add the flag -std=c++11.² After doing so, I could successfully compile the program using either GCC or clang++.

clang++’s error message

I think that clang++ is better than gcc in this case because the error message is brighter than the code. The word “warning” is in purple, while the ‘^’ is in yellow. This helps users to see what’s wrong.

temp1.cpp:9:16: warning: range-based for loop is a C++11 extension
      [-Wc++11-extensions]
    for (int i : bar) {
               ^
temp1.cpp:16:16: warning: range-based for loop is a C++11 extension
      [-Wc++11-extensions]
    for (int i : bar) {
               ^
2 warnings generated.

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