trunc function

Hi,

Code:

---

char format[64] = "1.51480724077861e-03";
char buffer[64] = "";
int number = 0;

printf("format [%s]\n", format);
        if(sscanf(format, "%s", &buffer) == 1)
        {
            number = sprintf(format, "%031.15f", atof(buffer));
        }
printf("return from sprintf [%d]\n", number);
printf("format [%s]\n", format);

---

/* OUTPUT */
[1.51480724077861e-03]
[31]
[000000000000000.001514807240779]


If I wanted the to establish the first whole number before the decimal place, what could I use ?

In the above example, the preferred output would be 0.001514807240779


tia,

>number = sprintf(format, "%031.15f", atof(buffer));
Change it to

Code:

---

number = sprintf(format, "%.15f", atof(buffer));

---

If you omit any formatting for the whole number, a single 0 is printed if there is none and the whole number is printed with no leading zeros if there is.

excellent :D


thanks twm

stuck on sprintf again,

(please note, that the dots are spaces but do not appear in the post, these values are all eight characters from a fixed length file)


I was hoping to change these values

[7.......]
[247371..]
[55......]

into these values

[.......7]
[..247371]
[......55]

using this

sprintf(output->usernbr, "%08ld", input->usernbr);

as they are left justified values I thought turning them to longs would pad them out, but unfortunately I am getting this

[-2684388]
[-2684388]
[-2684388]


can I use sprintf for this, or does every value have to be separetely manipulated ?



tia,

You can pad it out with either blanks or zero's with sprintf, it's a width specifier in the form of a number or 0number if you want leading zero's instead of blanks.

The format specifier for printf() and sprintf() strings are %n.ms. I can never remember in total exactly how the m and n affect the output so I wrote the following program:

Code:

---

#include <stdio.h>
#define NEXTCOL 38

char *strs      = "ABCDEF";
char *strl      = "ABCDEFGHIJKL";
int  sizesingle= 9;
int  size[][2]= {  3,  3,  -3,  3,    3,  9,  -3,  9,
                    3, -3,    3, -9,  -3, -3,  -3, -9,
                    3, 15,    3,-15,  -3, 15,  -3,-15,
                    0,  0,
                    9,  3,  -9,  3,  -9,  9,  -9, -3,
                    -9, -9,  -9, 15,  -9, -15,  9,  9,
                    9, -9,    9, -3,    9,  15,  9,-15,
                    0,  0,
                    15,  3,  15,  9,  15, -3,  15, -9,
                    15, 15,  15,-15,  -15,  3,  -15,  9,
                  -15, -9,  -15, 15,  -15,-15,  -15, -3,
                    -1,  0
                  };
char buf[20];
               
int main(int argc, char *argv[])
{
    int  i = 0;
    int  j;
   
    j = printf("  Short -- %d chars <%s> ", strlen(strs), strs);
    while (j++ < NEXTCOL)  putchar(' ');
    printf("  Long -- %d chars <%s>  \n", strlen(strl), strl);
    printf("\n");
   
    j = sprintf(buf,"%*s", sizesingle, strs);
    j = printf("      %%%3ds (%2d)  <%s> ", sizesingle, j, buf);
    while (j++ < NEXTCOL)  putchar(' ');
    j = sprintf(buf,"%*s", sizesingle, strl);
    j = printf("      %%%3ds (%2d)  <%s> ", sizesingle, j, buf);
    printf("\n");
   
    j = sprintf(buf,"%*s", -sizesingle, strs);
    j = printf("      %%%3ds (%2d)  <%s> ", -sizesingle, j, buf);
    while (j++ < NEXTCOL)  putchar(' ');
    j = sprintf(buf,"%*s", -sizesingle, strl);
    j = printf("      %%%3ds (%2d)  <%s> ", -sizesingle, j, buf);
    printf("\n");
   
    j = sprintf(buf,"%.*s", sizesingle, strs);
    j = printf("      %%.%2ds (%2d)  <%s> ", sizesingle, j, buf);
    while (j++ < NEXTCOL)  putchar(' ');
    j = sprintf(buf,"%.*s", sizesingle, strl);
    j = printf("      %%.%2ds (%2d)  <%s> ", sizesingle, j, buf);
    printf("\n");
   
    j = sprintf(buf,"%.*s", -sizesingle, strs);
    j = printf("      %%.%2ds (%2d)  <%s> ", -sizesingle, j, buf);
    while (j++ < NEXTCOL)  putchar(' ');
    j = sprintf(buf,"%.*s", -sizesingle, strl);
    j = printf("      %%.%2ds (%2d)  <%s> ", -sizesingle, j, buf);
    printf("\n");
   
    printf("\n");

    while (size[i][0] != -1)
    {
            if (size[i][0] != 0)
            {
            j = sprintf(buf,"%*.*s", size[i][0], size[i][1], strs);
            j = printf("  %%%3d.%3ds (%2d)  <%s> ", size[i][0], size[i][1], j, buf);
            while (j++ < NEXTCOL)  putchar(' ');
            j = sprintf(buf,"%*.*s", size[i][0], size[i][1], strl);
            j = printf("  %%%3d.%3ds (%2d)  <%s> ", size[i][0], size[i][1], j, buf);
        }
        printf("\n");
        i++;
    }
    printf("done... \n");
    return 0;
}

---

It will display a chart of all the positive & negative combinations of m & n

sorry chaps to be so long replying,

I was not able to get sprintf to do it, so I had to do this,

Code:

---


  ...snip...
  memcpy(output->usernbr, spacer(right_justify(input->usernbr, USERNBR_LEN, ZERO_INT), USERNBR_LEN), USERNBR_LEN);
  ...snip ...

char * right_justify(char * string, int length, int pad)
{
char buffer[BUFFER_SIZE + NULL_SIZE];
int count;
int found;

  memset(buffer, pad, BUFFER_SIZE);

  for(count = length, found = FALSE; count > 0 && !found; count--)
      if(*(string + (count - 1)) != SPACE_INT)
      {
        memcpy(buffer + (length - count), string, count);
        memcpy(string, buffer, length);
        found = TRUE;
      }

  if(!found)
      memset(string, pad, length);

  return(string);
}

char * spacer(char * string, int length)
{
int  count = 0;
int  found;

  for(count = 0, found = FALSE; count < (length - 1) && !found; count++)
  {
      if(*(string + count) == ZERO_INT)
        *(string + count) = SPACE_INT;
      else
        found = TRUE;
  }
    return(string);
}

---

this now changes these

Quote:

---

[7.......]
[247371..]
[55......]
[247372..]
[247373..]
[247374..]
[247378..]
[110.....]
[122.....]
[247373..]
[134.....]

---

into these

Quote:

---

[.......7]
[..247371]
[......55]
[..247372]
[..247373]
[..247374]
[..247378]
[.....110]
[.....122]
[..247373]
[.....134]

---

again, the dots are really spaces

>I was not able to get sprintf to do it

Code:

---

#include <stdio.h>
#include <stdlib.h>

void foo(char *dst, const char *src, int size)
{
  int value = atoi(src);
  sprintf(dst, "%*d", size, value);
}

int main(void)
{
  const char buffer[][9] =
  {
      "7      ","247371  ","55      ","247372  ","247373  ",
      "247374  ","247378  ","110    ","122    ","134    ",
  };
  size_t i;
  for(i = 0; i < sizeof buffer / sizeof *buffer; ++i)
  {
      char result[sizeof *buffer / sizeof **buffer];
      foo(result, buffer[i], sizeof result / sizeof *result - 1);
      printf("[%s] -> [%s]\n", buffer[i], result);
  }
  return 0;
}

/* my output
[7      ] -> [      7]
[247371  ] -> [  247371]
[55      ] -> [      55]
[247372  ] -> [  247372]
[247373  ] -> [  247373]
[247374  ] -> [  247374]
[247378  ] -> [  247378]
[110    ] -> [    110]
[122    ] -> [    122]
[134    ] -> [    134]
*/

---

???

yes Dave, it has worked for me too :D

sprintf(output->linkspeed, "%*d", LINKSPEED_LEN, atoi(input->linkspeed));

what I did not try before, was the atoi() function :(


thanks Dave,