CPP错误:表达式中的整数溢出 [英] CPP Error: Integer overflow in expression

问题描述

我试图以字节为单位表示16gb，而 uint64_t 抛出错误.

I'm trying to represent 16gb in bytes, and uint64_t throws an error.

我应该使用哪种数据类型来表示它? unsigned long int 也会引发错误.

What kind of data type should I use to represent it? unsigned long int also throws an error.

error: integer overflow in expression [-Werror=overflow]
         uint64_t TESTBYTES = 16 * 1024 * 1024 * 1024;

推荐答案

uint64_t TESTBYTES = 16ULL * 1024 * 1024 * 1024 可以做到.

否则，表达式 16 * 1024 * 1024 * 1024 被计算为 int ，由于溢出 int ，在您的平台上结果未定义类型.

Else the expression 16 * 1024 * 1024 * 1024 is evaluated as an int, with undefined results on your platform since you are overflowing the int type.

ULL 将第一个术语提升为 unsigned long long ，从而强制提升其他术语.这是始终的安全保证， unsigned long long 至少需要 64位.

ULL promotes the first term to an unsigned long long, forcing promotion of the other terms. This is always safe singe an unsigned long long needs to be at least 64 bits.

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