C++ 未签名的 _int64 的 sprintf
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sprintf for unsigned _int64
提问by venkysmarty
I am having following code. output of second %d in sprintf is always shown as zero. I think i am specifying wrong specifiers. Can any one help me in getting write string with right values. And this has to achieved in posix standard. Thanks for inputs
我有以下代码。sprintf 中第二个 %d 的输出始终显示为零。我想我指定了错误的说明符。任何人都可以帮助我获得具有正确值的写入字符串。这必须在 posix 标准中实现。感谢您的投入
void main() {
unsigned _int64 dbFileSize = 99;
unsigned _int64 fileSize = 100;
char buf[128];
memset(buf, 0x00, 128);
sprintf(buf, "\nOD DB File Size = %d bytes \t XML file size = %d bytes", fileSize, dbFileSize);
printf("The string is %s ", buf);
}
Output:
输出：
The string is
OD DB File Size = 100 bytes XML file size = 0 bytes
采纳答案by DevSolar
I don't know what POSIX has to say about this, but this is nicely handled by core C99:
我不知道 POSIX 对此有什么看法，但核心 C99 很好地处理了这一点：
#include <stdio.h>
#include <inttypes.h>
int main(void) {
uint64_t dbFileSize = 99;
uint64_t fileSize = 100;
char buf[128];
memset(buf, 0x00, 128);
sprintf( buf, "\nOD DB File Size = %" PRIu64 " bytes \t"
" XML file size = %" PRIu64 " bytes\n"
, fileSize, dbFileSize );
printf( "The string is %s\n", buf );
}
If your compiler isn't C99 compliant, get a different compiler. (Yes, I'm looking at you, Visual Studio.)
如果您的编译器不符合 C99，请使用其他编译器。（是的，我在看着你，Visual Studio。）
PS:If you are worried about portability, don'tuse %lld. That's for long long, but there are no guarantees that long longactually is the same as _int64(POSIX) or int64_t(C99).
PS：如果您担心便携性，请不要使用%lld. 那是为了long long，但不能保证long long实际上与_int64(POSIX) 或int64_t(C99) 相同。
Edit:Mea culpa - I more or less brainlessly "search & replace"d the _int64with int64_twithout really looking at what I am doing. Thanks for the comments pointing out that it's uint64_t, not unsigned int64_t. Corrected.
编辑：Mea culpa - 我或多或少无脑地“搜索和替换”了_int64with，int64_t而没有真正看我在做什么。感谢您的评论指出它是uint64_t，不是unsigned int64_t。更正。
回答by Shamim Hafiz
You need to use %I64uwith Visual C++.
您需要在Visual C++ 中使用%I64u。
However, on most C/C++ compiler, 64 bit integer is long long. Therefore, adopt to using long longand use %llu.
但是，在大多数 C/C++ 编译器上，64 位整数是 long long。因此，采用long long并使用%llu。
回答by Maxim Egorushkin
If you are looking for a portable solution, then use printf macrosfrom <inttypes.h>. You may need to define __STDC_FORMAT_MACROSto make these available in C++.
如果你正在寻找一个便携式解决方案，然后使用printf的宏从<inttypes.h>。您可能需要定义__STDC_FORMAT_MACROS以使这些在 C++ 中可用。
