CSC373/406: Integers: Types [5/9]

Primitive types in C include (with size in bytes, using gcc on x86)

declaration  size   values
char   f;     1      -128 to 127
short  c;     2      -32,768 to 32,767
int    a;     4      -2,147,483,648 to 2,147,483,647
long   b;     4      -2,147,483,648 to 2,147,483,647
float  d;     4      -3.4e38 to 3.4e38   //  7 decimal digits of precision
double e;     8      -1.7e308 to 1.7e308 // 15 decimal digits of precision 

int  h[20];  80      // array of 20 int  (20*4==80)
char i[20];  20      // array of 20 char (20*1==20)

sizeof operator tells you how many bytes something takes up

file:sizeof.c [source]

00001: #include <stdio.h> 00002: 00003: void fn(int x[ ]) { 00004: printf("In fn\nint array: %d\n", sizeof x); 00005: } 00006: 00007: int main() { 00008: int a; 00009: long b; 00010: short c; 00011: float d; 00012: double e; 00013: char f; 00014: int *g; 00015: int h[20]; 00016: printf("int: %d\nlong: %d\nshort: %d\nfloat: %d\n", 00017: sizeof a, sizeof b, sizeof c, sizeof d); 00018: printf("double: %d\nchar: %d\nint *: %d\nint array: %d\n", 00019: sizeof e, sizeof f, sizeof g, sizeof h); 00020: fn(h); 00021: return 0; 00022: } 00023:

An array parameter is really a pointer!