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Programming-Idioms

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  • C++

Idiom #43 Break outer loop

Look for a negative value v in 2D integer matrix m. Print it and stop searching.

Control flow jumping forward after the end of the outermost loop
#include <iostream>
auto indices = findNegativeValue (m, 10, 20);
std::cout << m[indices.first][indices.second] << '\n';

std::pair<int, int> findNegativeValue (int **m, int rows, int columns) {
  for (int i = 0; i < rows; ++i) {
    for (int j = 0; j < columns; ++j) {
      if (m[i][j] < 0) return make_pair (i, j);
    }
  }
  throw "No negative value!";
}

Whenever the code is as complicated as you need to break the outer loop, it is the correct time to add a new function.

edit: The above comment is an opinion and adds nothing to presenting a solution to the stated problem. It is a narrow-minded opinion to think such a statement can apply to every conceivable situation.
Outer_loop:
for A in M'Range (1) loop
   Inner_Loop:
   for B in M'Range (2) loop
      if M (A, B) < 0 then
         Put_Line (M (A, B)'Image);
         exit Outer_Loop;
      end if;
   end loop Inner_Loop;
end loop Outer_Loop;

New implementation...
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