The Significance of Integers in C

At a low level, different manufacturers employed different memory sizes for a basic character - some just 6 bits, some 8 bits, 9, and 10. The unfortunate outcome was the incompatability of computer programs and data storage formats.

The C programming language, developed in the early 1970s, addressed this issue by not defining the required size of its datatypes. Thus, C programs are portable at the level of their source code - porting a program to a different computer architecture is possible, provided that the programs are compiled on (or for) each architecture. The only requirement was that:

sizeof(char) ≤ sizeof(short) ≤ sizeof(int) ≤ sizeof(long)

Since the 1980s, fortunately, the industry has agreed on 8-bit characters or bytes. But (compiling and) running the C program on different architectures:

#include <stdio.h>

int main(void)
{
    printf("char  %lu\n", sizeof(char));
    printf("short %lu\n", sizeof(short));
    printf("int   %lu\n", sizeof(int));
    printf("long  %lu\n", sizeof(long));
    return 0;
}

char  1
short 2
int   4
long  8

Why does this matter? Different sized integers can store different maximum values - the above datatypes are signed (supporting positive and negative values) so a 4-byte integer can only represent the values -2,147,483,648 to 2,147,483,647.

If employing integers for 'simple' counting, or looping over a known range of values, there's rarely a problem. But if using integers to count many (small) values, such as milli- or micro-seconds, it matters:

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