long long int 溢出问题，求指导

[weixin_42382299]

#include "stdafx.h"
#include<stdio.h>
#include<math.h>
int main() {
int bytes_of_int;
int bits_of_int;
int biggest_of_int;
bytes_of_int = sizeof(int);
bits_of_int = bytes_of_int * 8;
biggest_of_int = pow(2, bits_of_int - 1) - 1;
printf("There are %d bytes in a int,equals %d bits,and it can signify %d at most.\n", bytes_of_int, bits_of_int, biggest_of_int);
printf("When overflow ,%d\n", biggest_of_int + 1);

short int bytes_of_short_int;
short int bits_of_short_int;
short int biggest_of_short_int;
bytes_of_short_int = sizeof(short int);
bits_of_short_int = bytes_of_short_int * 8;
biggest_of_short_int = pow(2, bits_of_short_int - 1) - 1;
printf("There are %hd bytes in a short int,equals %hd bits,and it can signify %hd at most.\n", bytes_of_short_int, bits_of_short_int, biggest_of_short_int);
printf("When overflow ,%hd\n", biggest_of_short_int + 1);

long int bytes_of_long_int;
long int bits_of_long_int;
long int biggest_of_long_int;
bytes_of_long_int = sizeof(long int);
bits_of_long_int = bytes_of_long_int * 8;
biggest_of_long_int = pow(2, bits_of_long_int - 1) - 1;
printf("There are %ld bytes in a long int,equals %ld bits,and it can signify %ld at most.\n", bytes_of_long_int, bits_of_long_int, biggest_of_long_int);
printf("When overflow ,%ld\n", biggest_of_long_int + 1);

long long int bytes_of_long_long_int;
long long int bits_of_long_long_int;
long long int biggest_of_long_long_int;
bytes_of_long_long_int = sizeof(long long int);
bits_of_long_long_int = bytes_of_long_long_int * 8;
biggest_of_long_long_int = pow(2, bits_of_long_long_int - 1) - 1;
printf("There are %lld bytes in a long long int,equals %lld bits,and it can signify %lld at most.\n", bytes_of_long_long_int, bits_of_long_long_int, biggest_of_long_long_int);
printf("When overflow ,%lld\n", biggest_of_long_long_int + 1);
long long int biggest_of_long_long_int_test = 9223372036854775807;
printf("%lld\n", biggest_of_long_long_int_test);
printf("%lld\n", biggest_of_long_long_int_test + 1);
getchar();
return 0;
}

[weixin_42382299]

[weixin_42382299]

图片倒数第四行，long long int 上限出了问题。同样的代码，用在short int ，int， long int，上没有出现问题，请问这个错误的结果是出在了哪里？

[wang0635]

编译器老点了吧？

[赵4老师]

浮点数格式 http://bbs.csdn.net/topics/390676437

[weixin_42382299]

引用 3 楼 wang0635 的回复:

编译器老点了吧？

新下载的VS2017，应该不会出问题吧？

[weixin_42382299]

引用 4 楼 zhao4zhong1 的回复:

浮点数格式 http://bbs.csdn.net/topics/390676437

好像不是有关浮点数的问题，整型溢出。 long long int bytes_of_long_long_int; long long int bits_of_long_long_int; long long int biggest_of_long_long_int; bytes_of_long_long_int = sizeof(long long int); bits_of_long_long_int = bytes_of_long_long_int * 8; biggest_of_long_long_int = pow(2, bits_of_long_long_int - 1) - 1; 好像是这段代码没有取得long long int的上限值。并且直接产生了溢出，biggest_of_long_long_int = pow(2, bits_of_long_long_int - 1) - 1;最后的-1好像没有生效。

[赵4老师]

2^63-1=9223372036854775807

[赵4老师]

pow函数的参数是double类型，double类型的有效数字个数是15 而 2^63=9223372036854775807 其有效数字个数已经超过15

[weixin_42382299]

引用 7 楼 zhao4zhong1 的回复:

pow函数的参数是double类型，double类型的有效数字个数是15 而 2^63=9223372036854775807 其有效数字个数已经超过15

谢谢！祝你明天没有BUG！