只获取没有 printf 的返回值

Question

I'm writing a program for a college assignment and one of the required functions needs to conditionally print a value and then return either 1 if it printed a value or 0 if it didn't print a value. In another required function, I have an array of values that may or may not be printed. If any single one of those values are not printed, all of them must not be printed. The problem is, I need to check through the array to see if any of them will not be printed using the first function. It wouldn't be a problem if the first value in the array will not be printed, but if the first few will be printed and then one of them won't be, it prints the first few while checking if any won't be printed, thus not meeting the requirements.

I know that was kind of confusing so here's some pseudocode:

short function1(value) {
    short retVal = 0;
    if (valueIsGood) {
        printf(value);
        retVal = 1;
    }
    return retVal;
}

short function2(array[]) {
    int i;
    for (i = 0; i < sizeof(array); i++) {
        if (function1(array[i]) == 0) {
            return "invalid";
        }
    }
}

If the array has values { goodValue1, goodValue2, badValue1, goodValue3 }, it prints goodValue1 and goodValue2 before returning invalid. I want a way for it to just return invalid. Thanks.

Answer 1

Think in a way of switching on/off a flag. Since it's an assignment, I will show you the algorithm in pseudo code only.

In first case the pseudo-code is:

set flag off
for each line
    if line is printable
        print line
        set flag on
    endif
endfor
if flag is on
    return 1
else
    return 0
endif

So now this will help you to construct the second function

set flag on
for each line
    if line is not printable
        set flag off
    endif
endfor
if flag is on
   for each line
      print line
   endfor
else
    return 0
endif