Error message: if the number is not integer but float

Question

Why the error does not occur when I put a float number?

int m;
if(scanf("%d%",&m)!=1)
{
    printf("Error\n");
    exit(1);
}

Depends on exactly how the "float" is given: For example, "1.2" can be (correctly) seen as an integer input (i.e. "1" - ignoring the rest); however, ".123" will most likely fail. — Adrian Mole
– Adrian Mole, Commented Mar 6, 2020 at 13:14
Maybe this post: C-Checking if input (float) is purely integer or float will be helpful? — Adrian Mole
– Adrian Mole, Commented Mar 6, 2020 at 13:16

Clifford · Accepted Answer · 2020-03-06 18:31:41Z

2

Because %d will consume all decimal digits until the first non-decimal digit. So if you enter "50.5" m will have the value 50 and the characters ".5" will remain in the buffer unread.

There are many possible solutions. Here's one:

int m ;
double fm ;

if( scanf("%f%",&fm) != 1 || 
    modf( fm, &m) != 0 )
{
    printf("Error\n");
    exit(1);
}

edited Mar 6, 2020 at 18:31

answered Mar 6, 2020 at 13:18

Clifford

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