C编程：用户输入标记值后，如何终止程序？

Question

so I first #define SENTINEL -1

and in a certain function, I set up an if statement

void blahblah(blah)
{
   printf("Enter an integer (-1 to quit)");
   scanf("%d", &value);
   if (value == SENTINEL)
     return;
}

but for some reason it's not terminating the program like I want it to?

Answer 1

return doesn't mean quit, it just means return from the function.... in your code there, the if statement is useless, because the function will return anyways if the if statement is false.

You probablly want to return a value from blahbalh to say to quit.

Answer 2

If you wish your entire program to terminate, please replace return with a exit(0); . Also, please ensure that the data type of value is int and not unsigned int .

Answer 3

The normal way would be to set a flag to cause a return; in main() - but you can use exit() to immediately abort a program from any part of the code.

Be aware that if you use exit() the program will just end there and you wont get any termination/clean up code you might want to run.

edit again, was thinking in the wrong language! exit() expects an int parameter signifying the status of the return, either EXIT_SUCCESS or EXIT_FAILURE

my bad!

Answer 4

There is no reason for program to terminate, you are only leaving (return) a function when value == SENTINEL.

You function also has three problems; if value != SENTINEL then you don't return a function which is undefined behaviour; parameter blah is missing a type (int blah) ; and value should be global for that function to work.