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封装 printf

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[root@localhost ~]# cat print.c
#include "stdio.h"
#include <stdarg.h>

void WriteLog(const char *format, ...)
{
    char buff[2048];
    const int size = sizeof(buff);

    va_list args;
    va_start(args, format);
    vsnprintf(buff, size, format, args);
    va_end(args);

    printf(buff);
}


int main()
{
    printf(  "linux:[%f][%s][%d][%zd][%4d]\n", 1/3.0, "hello", 1992, 0x00FFFFFFFFFF, 42);
    WriteLog("linux:[%f][%s][%d][%zd][%4d]\n", 1/3.0, "hello", 1992, 0x00FFFFFFFFFF, 42);

    return 0;
}

编译运行

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[root@localhost ~]# gcc -Wall print.c && ./a.out
linux:[0.333333][hello][1992][1099511627775][  42]
linux:[0.333333][hello][1992][1099511627775][  42]
[root@localhost ~]#
[root@localhost ~]#

截断显示

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[root@localhost ~]# cat print.c
#include "stdio.h"
int main()
{
    // 5字符, 左对齐, 只显示2字符
    printf("%-*.*s\n", 5,2,"123");
    return 0;
}



[chunli@localhost ~]$ gcc /tmp/main.c -o /tmp/main.c.o
[chunli@localhost ~]$ /tmp/main.c.o
12
[chunli@localhost ~]$