Question

How i can know the size of all data type in my computer?

Answer 1

The following program should do the trick for the primitive types:

#include <stdio.h>
int main()
{
    printf("sizeof(char) = %d\n", sizeof(char));
    printf("sizeof(short) = %d\n", sizeof(short));
    printf("sizeof(int) = %d\n", sizeof(int));
    printf("sizeof(long) = %d\n", sizeof(long));
    printf("sizeof(long long) = %d\n", sizeof(long long));
    printf("sizeof(float) = %d\n", sizeof(float));
    printf("sizeof(double) = %d\n", sizeof(double));
    printf("sizeof(long double) = %d\n", sizeof(long double));
    return 0;
}

This prints the number of “bytes” the type uses, with sizeof(char) == 1 by definition. Just what 1 means (that is how many bits that is) is implementation specific and likely depend on the underlying hardware. Some machines have 7 bit bytes for instance, some have 10 or 12 bit bytes.