Lesson 6 / 38

Data Types

Know the sizes of char, int, float and double, measure them with sizeof and avoid overflow surprises.

The basic types

char 1 byte · int 4 bytes · float 4 bytes · double 8 bytes · bool via <stdbool.h>. Modifiers: short, long, long long, unsigned.

sizeof reports bytes at compile time.

#include <stdio.h>
int main(void) {
    printf("int is %zu bytes\n", sizeof(int));
    return 0;
}

Output:

int is 4 bytes

unsigned char c = 255; c = c + 1; makes c become 0. Integer types wrap around at their limits.