Why are my C programs running perfect in the compiler but the .exe of them runs then crashes?

I have tried running the .exe of multiple programs that run and work perfect in my compiler (codeblocks) but when I run the .exe of the file they begin running but crash eventually. The .exe of this calculator for example crashes when it is supposed to display the answer, but works fine in my compiler.

#include <stdio.h>
#include <stdlib.h>
float Add(float num1, float num2){
return num1 + num2;
}
float Subtract(float num1, float num2){
return num1 - num2;
}
float Multiply(float num1, float num2){
return num1 * num2;
}
float Divide(float num1, float num2){
return num1 / num2;
}
int main()
{
while(1){
int selection;
float num1, num2, answer;
char* selectionNames[] = {"Addition", "Subtraction", "Multiplication", "Division"};
printf("Select Function from List:\n1: Addition\n2: Subtraction\n3: Multiplication\n4:     Division\nSelection: ");
scanf("%d", &selection);
if(selection < 1 || selection > 4) {
printf("Please choose a valid operator!");
return 1;
}
if (selection == 0) {
printf("Exiting...\n");
break;
}
printf("You have Selected %s\n\n", selectionNames[selection-1]);
printf("Enter First Number: ");
scanf("%f", &num1);
printf("Enter Second Number: ");
scanf("%f", &num2);
switch (selection){
case 1:
answer = Add(num1,num2);
printf("\nAnswer = %.2f", answer);
break;
case 2:
answer = Subtract(num1,num2);
printf("\nAnswer = %.2f", answer);
break;
case 3:
answer = Multiply(num1,num2);
printf("\nAnswer = %.2f", answer);
break;
case 4:
if (num2 == 0) {
printf("Cannot divide by zero!\n\n");
continue;
}
answer = Divide(num1,num2);
printf("\nAnswer = %.2f", answer);
break;
}
return 0;
}
}

The program works fine in my compiler but the .exe file for it crashes before it displays the answer, it takes 3 user inputs before the crash.

There are two different problems:

1. Your program is supposed to run in a loop (why would there be a while(1) otherwise?), however, you have a return statement inside the loop block (just put it outside). Note that this isn't what is generally understood as "crashing", and its just a bug causing undesired behavior.

2. When you run a console application by clicking twice on it, the window will immediately close as soon as the program is done with its execution (which doesn't happen on your IDE because you have a permanent terminal). This abrupt window closing may be seem as a sign that the app is "crashing", but in this case it is not. It may be a good idea to add a simple prompt before the end of the program, to give your users a chance to read your program's last words:

int main() {
  // ...
  printf("[press enter]");
  getchar();
  return 0;
}