Can I check that the function worked?

[chronospear]

Hello
When I code a program, sometimes I confront this problem.

Psudocode is this.

void FuncA() {blah blah...}
void FuncB() {blah blah...}
void main()
{
  if(FuncA() is worked)
   make FuncB() work;
}

My question is this.
'FuncA() is worked' is can be typed boolean?

Thx for reading! :)

[MrHutch]

Sure, just have FuncA return a bool.

bool FuncA()
{
   // Return true or false for success/fail
}

Then you can assess the return value in an if statement.
if( FuncA() ) { /* FuncA returned true */ }
or...
if( !FuncA() ) { /* FuncA returned false */ }

[kbw]

FuncA() can return a bool or any integral type (that is, int, long, short, ...). C treats zero as false, and non-zero as true.

[chronospear]

Thx for answer! ^^

but, in case that FuncA, FuncB need to return the values[int, double, string... whatever],
then this way can't be used, right?

For example...

int FuncA(int x)
{
int valueA = (x)*(x);
return valueA;
}
int FuncB(int x)
{
int valueB = (x)*(x)*(x);
return valueB;
}

[MrHutch]

Well, there are still a bunch of ways you could check return types or set status flags.

#include <iostream>
#include <string>

// Return an integer
int FuncA( int n )
{
  return n * n;
}

// Return a string
std::string FuncB()
{
  return "Yay!";
}

// Return a bool, take integer reference
bool FuncC( int &ret )
{
  ret *= ret;
  return true;
}

// Return an int, take int and bool reference
int FuncD( int n, bool &status )
{
  status = true;
  return n * n;
}

int main( int argc, char *argv[] )
{
  int a = 10;
  bool status = false;

  if( FuncA( a ) > 0 )
    std::cout << "FuncA returned greater than zero\n";

  if( FuncB() == "Yay!" )
    std::cout << "FuncB returned \"Yay\"\n";

  if( FuncC( a ) )
    std::cout << "FuncC returned true, a is " << a << std::endl;

  a = FuncD( a, status );

  if( status )
    std::cout << "FuncD set status to true, a is " << a << std::endl;

  return 0;
}

[chronospear]

Ah, thx again iHutch105

In this case, what if the functions are not user-definition, but built-in functions?

Like,sqrt() (um, I can't give an another example right now...) and so on...

[PavDub]

First ask yourself what you exactly mean by FuncA() is worked
Then check for this condition... ;)

---

a] realize that there are number of functions that simply cannot "not work"
- then you may be interested in the result rather than actual functionality

b] those function that can "not work" usually either
- return bool
- return an errorcode integer
- set up a global errorcode indicator (deprecated - not thread safe bhv )
- throw exception

b.1] If it is your choice, choose any
b.2] If somebody else did, read documentation

[MrHutch]

Built in functions will have their own prototypes. It really depends on what they do already.

For example, sqrt can only return whatever the prototype defines; a double, float or whatever.

If you take a look at the reference^[1] for it you can see how it handles what it considers would be failures (for example, passing in a negative value). In the case of sqrt, the global errno variable is set to EDOM to flag a domain error.

[1] http://www.cplusplus.com/reference/cmath/sqrt/

[BigBlackSheep]

You could also throw if the function encountered a problemo.