C語言數據類型探究

數據類型大小

類型	大小
char	1
short	2
short int	2
int	4
long	4
long long	8
float	4
double	8
long double	12

#include "stdio.h"

int main(void)
{
	char *cp_test;
	int *intp_test;

	printf("size of (unsigned char) is %d\n", sizeof(unsigned char));
	printf("size of (short) is %d\n", sizeof(short));
	printf("size of (int) is %d\n", sizeof(int));
	printf("size of (long) is %d\n", sizeof(long));
	printf("size of (long long) is %d\n", sizeof(long long));
	printf("size of (float) is %d\n", sizeof(float));
	printf("size of (double) is %d\n", sizeof(double));
	printf("size of (long double) is %d\n", sizeof(long double));
	printf("size of (char pointer) is %d\n", sizeof(cp_test));
	printf("size of (int pointer) is %d\n", sizeof(intp_test));
	return 0;
}

運行結果：

size of (unsigned char) is 1
size of (short) is 2
size of (int) is 4
size of (long) is 4
size of (long long) is 8
size of (float) is 4
size of (double) is 8
size of (long double) is 12
size of (char pointer) is 4
size of (int pointer) is 4

數據類型轉換

數據類型隱式轉換

隱式轉換規則

• 位數少的轉換爲位數多的數據結構
• 浮點數類型均先轉換爲double雙精度數據類型，再進行運算。
• char和short類型先轉換爲int類型，再進行運算。
• 若參與運算量的類型不同，則先轉換成同一類型，然後進行運算。

數據類型強制轉換

• 位數多的強制轉換爲位數少的數據類型，轉換後的數據類型保留低位數據。
• 存在截斷效應，會導致數據精度的丟失

隨筆

• 可以通過sizeof得出指針的大小，從而獲得系統的位數，因爲指針存儲的內容爲地址。