如何在 C 中打印 int64_t 类型 [英] How to print a int64_t type in C

问题描述

C99 标准具有整数类型，其字节大小类似于 int64_t.我目前使用的是 Windows 的 %I64d 格式(或未签名的 %I64u)，例如:

C99 standard has integer types with bytes size like int64_t. I am using Windows's %I64d format currently (or unsigned %I64u), like:

#include <stdio.h>
#include <stdint.h>
int64_t my_int = 999999999999999999;
printf("This is my_int: %I64d
", my_int);

我收到这个编译器警告:

and I get this compiler warning:

warning: format ‘%I64d’ expects type ‘int’, but argument 2 has type ‘int64_t’

我尝试过:

printf("This is my_int: %lld
", my_int); // long long decimal

但我收到了同样的警告.我正在使用这个编译器:

But I get the same warning. I am using this compiler:

~/dev/c$ cc -v
Using built-in specs.
Target: i686-apple-darwin10
Configured with: /var/tmp/gcc/gcc-5664~89/src/configure --disable-checking --enable-werror --prefix=/usr --mandir=/share/man --enable-languages=c,objc,c++,obj-c++ --program-transform-name=/^[cg][^.-]*$/s/$/-4.2/ --with-slibdir=/usr/lib --build=i686-apple-darwin10 --program-prefix=i686-apple-darwin10- --host=x86_64-apple-darwin10 --target=i686-apple-darwin10 --with-gxx-include-dir=/include/c++/4.2.1
Thread model: posix
gcc version 4.2.1 (Apple Inc. build 5664)

我应该使用哪种格式在没有警告的情况下打印 my_int 变量?

Which format should I use to print my_int variable without having a warning?

推荐答案

对于 int64_t 类型:

#include <inttypes.h>
int64_t t;
printf("%" PRId64 "
", t);

对于 uint64_t 类型:

#include <inttypes.h>
uint64_t t;
printf("%" PRIu64 "
", t);

您也可以使用 PRIx64 以十六进制打印.

you can also use PRIx64 to print in hexadecimal.

cppreference.com 拥有所有类型的可用宏的完整列表，包括intptr_t (PRIxPTR).scanf 有单独的宏，例如 SCNd64.

cppreference.com has a full listing of available macros for all types including intptr_t (PRIxPTR). There are separate macros for scanf, like SCNd64.

PRIu16 的典型定义是 "hu"，因此隐式字符串常量连接发生在编译时.

A typical definition of PRIu16 would be "hu", so implicit string-constant concatenation happens at compile time.

为了让你的代码完全可移植，你必须使用 PRId32 等来打印 int32_t 和 "%d" 或类似的用于打印 int.

For your code to be fully portable, you must use PRId32 and so on for printing int32_t, and "%d" or similar for printing int.

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