c problem

[Amit Sharma]

#include<conio.h>
#include<stdio.h>
void main()
{
float a=7.2;
clrscr();
if(a < 7.2)
printf("Lesser" );
else
printf("Greater Or Equal");
getch();
}
Output::
Lesser

So please check it the answer of the program come right only if we add
if(a<7.2f) on the place of if(a<7.2)

[horace1]

floating point numbers are stored within the computer in binary floating point format to a certain number of significant figures, for example typical values for a 32 bit float variable is 6 significant decimal figures and 64 bit double is 15 significant decimal figures.
Hence 7.2 when in a binary format may be stored inside the computer as 7.199999

in the code

float a=7.2;
 

a is initialised to to float value 7.2 (to 6 significant figures)

however, in the comparision

if(a < 7.2)
 

7.2 is a double constant, a is converted to a double for the < comparision which causes the problem

consider

float a=7.2;
double b=7.2;
printf("%20.15lf\n" ,(double)a);
printf("%20.15lf\n", b);
 

prints
7.199999809265137
7.200000000000000

here we see that when a (float value 7.2) is converted to a double its value is less than b (double value 7.2) which is why you program says a is less than 7.2.

if you change the test to

if(a < 7.2f)
 

you are comparing a float with a float

[Amit Sharma]

Thanks sir.