我可以用printf打印十六进制或八进制数字。是否有格式标签打印为二进制或任意基数?

我正在运行gcc。

printf("%d %x %o\n", 10, 10, 10); //prints "10 A 12\n"
printf("%b\n", 10); // prints "%b\n"

当前回答

根据@William Whyte的回答,这是一个提供int8、16,32和64版本的宏,重用int8宏以避免重复。

/* --- PRINTF_BYTE_TO_BINARY macro's --- */
#define PRINTF_BINARY_PATTERN_INT8 "%c%c%c%c%c%c%c%c"
#define PRINTF_BYTE_TO_BINARY_INT8(i)    \
    (((i) & 0x80ll) ? '1' : '0'), \
    (((i) & 0x40ll) ? '1' : '0'), \
    (((i) & 0x20ll) ? '1' : '0'), \
    (((i) & 0x10ll) ? '1' : '0'), \
    (((i) & 0x08ll) ? '1' : '0'), \
    (((i) & 0x04ll) ? '1' : '0'), \
    (((i) & 0x02ll) ? '1' : '0'), \
    (((i) & 0x01ll) ? '1' : '0')

#define PRINTF_BINARY_PATTERN_INT16 \
    PRINTF_BINARY_PATTERN_INT8              PRINTF_BINARY_PATTERN_INT8
#define PRINTF_BYTE_TO_BINARY_INT16(i) \
    PRINTF_BYTE_TO_BINARY_INT8((i) >> 8),   PRINTF_BYTE_TO_BINARY_INT8(i)
#define PRINTF_BINARY_PATTERN_INT32 \
    PRINTF_BINARY_PATTERN_INT16             PRINTF_BINARY_PATTERN_INT16
#define PRINTF_BYTE_TO_BINARY_INT32(i) \
    PRINTF_BYTE_TO_BINARY_INT16((i) >> 16), PRINTF_BYTE_TO_BINARY_INT16(i)
#define PRINTF_BINARY_PATTERN_INT64    \
    PRINTF_BINARY_PATTERN_INT32             PRINTF_BINARY_PATTERN_INT32
#define PRINTF_BYTE_TO_BINARY_INT64(i) \
    PRINTF_BYTE_TO_BINARY_INT32((i) >> 32), PRINTF_BYTE_TO_BINARY_INT32(i)
/* --- end macros --- */

#include <stdio.h>
int main() {
    long long int flag = 1648646756487983144ll;
    printf("My Flag "
           PRINTF_BINARY_PATTERN_INT64 "\n",
           PRINTF_BYTE_TO_BINARY_INT64(flag));
    return 0;
}

这个输出:

My Flag 0001011011100001001010110111110101111000100100001111000000101000

为了可读性,你可能需要为eg添加分隔符:

My Flag 00010110,11100001,00101011,01111101,01111000,10010000,11110000,00101000

其他回答

我优化了顶部的解决方案的大小和c++ -ness,并得到了这个解决方案:

inline std::string format_binary(unsigned int x)
{
    static char b[33];
    b[32] = '\0';

    for (int z = 0; z < 32; z++) {
        b[31-z] = ((x>>z) & 0x1) ? '1' : '0';
    }

    return b;
}

之前发布的答案都不是我想要的,所以我写了一个。在printf中使用%B是超级简单的!

/*
 * File:   main.c
 * Author: Techplex.Engineer
 *
 * Created on February 14, 2012, 9:16 PM
 */

#include <stdio.h>
#include <stdlib.h>
#include <printf.h>
#include <math.h>
#include <string.h>

static int printf_arginfo_M(const struct printf_info *info, size_t n, int *argtypes)
{
    /* "%M" always takes one argument, a pointer to uint8_t[6]. */
    if (n > 0) {
        argtypes[0] = PA_POINTER;
    }
    return 1;
}

static int printf_output_M(FILE *stream, const struct printf_info *info, const void *const *args)
{
    int value = 0;
    int len;

    value = *(int **) (args[0]);

    // Beginning of my code ------------------------------------------------------------
    char buffer [50] = "";  // Is this bad?
    char buffer2 [50] = "";  // Is this bad?
    int bits = info->width;
    if (bits <= 0)
        bits = 8;  // Default to 8 bits

    int mask = pow(2, bits - 1);
    while (mask > 0) {
        sprintf(buffer, "%s", ((value & mask) > 0 ? "1" : "0"));
        strcat(buffer2, buffer);
        mask >>= 1;
    }
    strcat(buffer2, "\n");
    // End of my code --------------------------------------------------------------
    len = fprintf(stream, "%s", buffer2);
    return len;
}

int main(int argc, char** argv)
{
    register_printf_specifier('B', printf_output_M, printf_arginfo_M);

    printf("%4B\n", 65);

    return EXIT_SUCCESS;
}

至于我,我为此编写了一些通用代码

#include<stdio.h>
void int2bin(int n, int* bin, int* bin_size, const int  bits);

int main()
{
    char ch;
    ch = 'A';
    int binary[32];
    int binary_size = 0;
    
    int2bin(1324, binary, &binary_size, 32);
    for (int i = 0; i < 32; i++)
    {
        printf("%d  ", binary[i]);
    }
    
    
    return 0;
}

void int2bin(int n, int* bin,int *bin_size,const int  bits)
{
    int i = 0;
    int temp[64];
    for (int j = 0; j < 64; j++)
    {
        temp[j] = 0;
    }
    for (int l = 0; l < bits; l++)
    {
        bin[l] = 0;
    }

    while (n > 0)
    {
        temp[i] = n % 2;
        n = n / 2;
        i++;
    }
    *bin_size = i;

    //reverse modulus values
    for (int k = 0; k < *bin_size; k++)
    {
        bin[bits-*bin_size+k] = temp[*bin_size - 1 - k];
    }
}

根据@William Whyte的回答,这是一个提供int8、16,32和64版本的宏,重用int8宏以避免重复。

/* --- PRINTF_BYTE_TO_BINARY macro's --- */
#define PRINTF_BINARY_PATTERN_INT8 "%c%c%c%c%c%c%c%c"
#define PRINTF_BYTE_TO_BINARY_INT8(i)    \
    (((i) & 0x80ll) ? '1' : '0'), \
    (((i) & 0x40ll) ? '1' : '0'), \
    (((i) & 0x20ll) ? '1' : '0'), \
    (((i) & 0x10ll) ? '1' : '0'), \
    (((i) & 0x08ll) ? '1' : '0'), \
    (((i) & 0x04ll) ? '1' : '0'), \
    (((i) & 0x02ll) ? '1' : '0'), \
    (((i) & 0x01ll) ? '1' : '0')

#define PRINTF_BINARY_PATTERN_INT16 \
    PRINTF_BINARY_PATTERN_INT8              PRINTF_BINARY_PATTERN_INT8
#define PRINTF_BYTE_TO_BINARY_INT16(i) \
    PRINTF_BYTE_TO_BINARY_INT8((i) >> 8),   PRINTF_BYTE_TO_BINARY_INT8(i)
#define PRINTF_BINARY_PATTERN_INT32 \
    PRINTF_BINARY_PATTERN_INT16             PRINTF_BINARY_PATTERN_INT16
#define PRINTF_BYTE_TO_BINARY_INT32(i) \
    PRINTF_BYTE_TO_BINARY_INT16((i) >> 16), PRINTF_BYTE_TO_BINARY_INT16(i)
#define PRINTF_BINARY_PATTERN_INT64    \
    PRINTF_BINARY_PATTERN_INT32             PRINTF_BINARY_PATTERN_INT32
#define PRINTF_BYTE_TO_BINARY_INT64(i) \
    PRINTF_BYTE_TO_BINARY_INT32((i) >> 32), PRINTF_BYTE_TO_BINARY_INT32(i)
/* --- end macros --- */

#include <stdio.h>
int main() {
    long long int flag = 1648646756487983144ll;
    printf("My Flag "
           PRINTF_BINARY_PATTERN_INT64 "\n",
           PRINTF_BYTE_TO_BINARY_INT64(flag));
    return 0;
}

这个输出:

My Flag 0001011011100001001010110111110101111000100100001111000000101000

为了可读性,你可能需要为eg添加分隔符:

My Flag 00010110,11100001,00101011,01111101,01111000,10010000,11110000,00101000

下面是一个不受重入性问题或参数大小/类型限制的函数版本:

#define FMT_BUF_SIZE (CHAR_BIT*sizeof(uintmax_t)+1)

char *binary_fmt(uintmax_t x, char buf[static FMT_BUF_SIZE])
{
    char *s = buf + FMT_BUF_SIZE;
    *--s = 0;
    if (!x) *--s = '0';
    for (; x; x /= 2) *--s = '0' + x%2;
    return s;
}

请注意,这段代码适用于2到10之间的任何底数,只要将2替换为所需的底数。用法是:

char tmp[FMT_BUF_SIZE];
printf("%s\n", binary_fmt(x, tmp));

其中x是任意的积分表达式。