when storing a large positive integer it is converting to different negative number

Question

When i storing a large positive integer in unsigned long int in c, then it unknowingly converting to negative number.

for example

 a=2075000020, b=10000         


        

Answer 1

You cannot have been printing an unsigned integer, because it has printed a sign. Even if you declare the variable as unsigned, once it is on the stack for printf() to use, it is interpreted as a binary value to be used as specified by the format in printf().

Note the difference between these, and the results. In the the third example, you can see that bit 31 is set, which is the sign bit for signed long int.

#include 
#include 

int main () {
    unsigned long int a=2075000020, b=100000000, c;
    c = a + b;
    printf ("Signed %ld\n", c);
    printf ("Unsigned %lu\n", c);
    printf ("Hexadecimal 0x%lX\n", c);
    return 0;
}

Program output:

Signed -2119967276
Unsigned 2175000020
Hexadecimal 0x81A3DDD4