I_have_nothing wrote:

Is there any easy way to printf an integer in a way like 1,234,567?

I know "%d" can be usd to print it as 1234567.

Any type field in format specification can do that?

Or any easy way to do that?

How about to do that same thing in float type?

such as make 987564321.85 into 987,564,321.85 ?

Try this. Compile with TESTING defined for a demo driver.

#ifndef putnums_h_ /* --- file putnums.h --- */

# define putnums_h_

# ifdef __cplusplus

extern "C" {

# endif

/* Using binary as an example, code to ourput numbers

in a field, while injecting commas at intervals.

By C.B. Falconer. Put in public domain. 2003-02-15

*/

/* ------------------- */

/* Negative field for left justification, 0 based */

/* clump is interval for group separator, 0 for none */

int putnum(FILE *fp, long v, int base,

int field, int clump);

/* ------------------- */

/* Negative field for left justification, 0 based */

/* clump is interval for group separator, 0 for none */

int putunum(FILE *fp, unsigned long v, int base,

int field, int clump);

/* Macros to ease use for decimal output */

#define putdnum(fp, v, field, clump) \

putnum(fp, v, 10, field, clump)

#define putudnum(fp, v, field, clump) \

putunum(fp, v, 10, field, clump)

# ifdef __cplusplus

}

# endif

#endif

/* --- end putnums.h --- */

/* --- file putnums.c ---

Using binary as an example, code to ourput numbers

in a field, while injecting commas at intervals.

By C.B. Falconer. Put in public domain. 2003-02-15

*/

#include <stdio.h>

#include "putnums.h"

#ifdef TESTING /* Add in a demonstration driver */

# include <limits.h>

# define BASE 10 /* Try 2 through 16 here only */

# define GROUP 3 /* with 0, 4 or 3 here */

#endif

/* ------------------- */

/* The original call must pass in depth == 0 */

/* field is zero based, so 36 allows 37 chars */

static int putval(FILE *fp, unsigned long v, int base,

int field, int clump, int neg,

int depth)

{

int retval;

static char hexchars[16] = "0123456789abcdef";

if (depth && clump && ((depth % clump) == 0)) field--;

if ((v / base) > 0) {

retval = 1 + putval(fp, v/base, base, field,

clump, neg, depth+1);

}

else {

if (neg) field--;

while (field > depth) {

putc(' ', fp);

field--;

}

if (neg) {

putc('-', fp);

retval = 2;

}

else retval = 1;

}

/* Revise this for base value larger than 16 */

putc((v % base)[hexchars], fp);

if (depth && clump && ((depth % clump) == 0)) {

putc(',', fp);

retval++;

}

return retval;

} /* putval */

/* ------------------- */

/* Negative field for left justification, 0 based */

/* clump is interval for group separator, 0 for none */

int putnum(FILE *fp, long v, int base,

int field, int clump)

{

int retval;

if (v < 0) retval = putval(fp, -v, base, field, clump, 1, 0);

else retval = putval(fp, v, base, field, clump, 0, 0);

while ((field + retval) <= 0) {

field++;

putc(' ', fp);

}

return retval;

} /* putnum */

/* ------------------- */

/* Negative field for left justification, 0 based */

/* clump is interval for group separator, 0 for none */

int putunum(FILE *fp, unsigned long v, int base,

int field, int clump)

{

int retval;

retval = putval(fp, v, base, field, clump, 0, 0);

while ((field + retval) <= 0) {

field++;

putc(' ', fp);

}

return retval;

} /* putunum */

/* ------------------- */

#ifdef TESTING

int main(void)

{

int i, lgh;

for (i = 0; i < 50; i++) putchar('0' + i % 10);

putchar('\n');

for (i = 0; i < 12; i++) {

lgh = putnum(stdout, i, BASE, 36, GROUP);

putchar(' ');

lgh = putnum(stdout, lgh, BASE, 8, GROUP);

puts(".");

}

i = INT_MAX - 4;

do {

i++;

lgh = putnum(stdout, i, BASE, 36, GROUP);

putchar(' ');

lgh = putnum(stdout, lgh, BASE, 8, GROUP);

puts(".");

} while (i < INT_MAX);

i = INT_MIN + 4;

do {

i--;

lgh = putnum(stdout, i, BASE, 36, GROUP);

putchar(' ');

lgh = putnum(stdout, lgh, BASE, 8, GROUP);

puts(".");

lgh = putunum(stdout, (unsigned long)i, BASE, 36, 0);

putchar(' ');

lgh = putnum(stdout, lgh, BASE, 8, GROUP);

puts(".");

} while (i > INT_MIN);

lgh = putunum(stdout, 1, BASE, -36, GROUP);

putchar(' ');

lgh = putunum(stdout, lgh, BASE, 8, GROUP);

puts(".");

for (i = 0; i < 4; i++) {

lgh = putudnum(stdout, (unsigned long)-i, 36, GROUP);

putchar(' ');

lgh = putdnum(stdout, lgh, 8, GROUP);

puts(".");

lgh = putunum(stdout, (unsigned long)-i, 16, 36, 4);

putchar(' ');

lgh = putunum(stdout, lgh, BASE, -8, GROUP);

puts(".");

lgh = putunum(stdout, (unsigned long)-i, 2, -36, 4);

putchar(' ');

lgh = putunum(stdout, lgh, BASE, 8, GROUP);

puts(".");

}

return 0;

} /* main */

#endif

/* --- end putnums.c --- */

--

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