C++ 错误：“INT32_MAX”未在此范围内声明
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error: 'INT32_MAX' was not declared in this scope
提问by jm1234567890
I'm getting the error
我收到错误
error: 'INT32_MAX' was not declared in this scope
But I have already included
但我已经包括
#include <stdint.h>
I am compiling this on (g++ (GCC) 4.1.2 20080704 (Red Hat 4.1.2-44) with the command
我正在使用命令在 (g++ (GCC) 4.1.2 20080704 (Red Hat 4.1.2-44) 上编译它
g++ -m64 -O3 blah.cpp
Do I need to do anything else to get this to compile? or is there another C++ way to get the constant "INT32_MAX"?
我需要做任何其他事情来编译它吗？还是有另一种 C++ 方法来获取常量“ INT32_MAX”？
Thanks and let me know if anything is unclear!
谢谢，如果有什么不清楚的，请告诉我！
采纳答案by doc
#include <cstdint> //or <stdint.h>
#include <limits>
std::numeric_limits<std::int32_t>::max();
Note that <cstdint>is a C++11 header and <stdint.h>is a C header, included for compatibility with C standard library.
请注意，这<cstdint>是一个 C++11 头文件，并且<stdint.h>是一个 C 头文件，为了与 C 标准库兼容而包含在内。
Following code works, since C++11.
以下代码有效，自 C++11 起。
#include <iostream>
#include <limits>
#include <cstdint>
struct X
{
static const std::int32_t i = std::numeric_limits<std::int32_t>::max();
};
int main()
{
switch(std::numeric_limits<std::int32_t>::max()) {
case std::numeric_limits<std::int32_t>::max():
std::cout << "this code works thanks to constexpr\n";
break;
}
return EXIT_SUCCESS;
}
回答by Blindy
Quoted from the man page, "C++ implementations should define these macros only when __STDC_LIMIT_MACROSis defined before <stdint.h>is included".
引用自手册页，“C++ 实现应仅在包含__STDC_LIMIT_MACROS之前定义时定义这些宏<stdint.h>”。
So try:
所以尝试：
#define __STDC_LIMIT_MACROS
#include <stdint.h>
回答by pixelpax
Hm... All I needed to do was #include <climits>nothing else on this page worked for me.
嗯...我需要做的就是#include <climits>这个页面上没有其他东西对我有用。
Granted, I was trying to use INT_MIN.
当然，我正在尝试使用INT_MIN.
回答by Rahul Dutta
#include <iostream>
#include <limits.h> or <climits>
worked for me
为我工作
回答by Ram
I ran into similar issue while using LLVM 3.7.1 c++ compiler. Got the following error while trying to compile gRPC code as part of building some custom library
我在使用 LLVM 3.7.1 c++ 编译器时遇到了类似的问题。尝试编译 gRPC 代码作为构建某些自定义库的一部分时出现以下错误
src/core/lib/iomgr/exec_ctx.h:178:12: error: use of undeclared identifier 'INT64_MAX'
The compilation went through after adding -D__STDC_LIMIT_MACROSas one of the options to c++ compiler.
在添加-D__STDC_LIMIT_MACROS为 c++ 编译器的选项之一后，编译通过。
.../bin/c++ -D__STDC_LIMIT_MACROS -I{LIBRARY_PATHS} testlib.cc -o testlib
回答by hardik chugh
I was also facing the similar problem,just need to add-
#include <limits.h>after #include <iostream>
我也遇到了类似的问题，只需要在#include <limits.h>后面加上-
#include <iostream>
回答by hardik chugh
Including the following code after #include <iostream>worked for me:
#include <iostream>在为我工作后包括以下代码：
#include <limits.h>
I am using the following compiler:
我正在使用以下编译器：
g++ 5.4.0-6
克++ 5.4.0-6
