Help discarding a space in char array

[cjohnman]

I have some embedded sql code that reads data from a sql database and inserts the data into a ingres isql database. That works fine. My problem lies in the code when I use atof to convert a character field (set up by outside company) in sql to a double for the ingres database. This value should have been an integer in SQL as well. So I store this char field from sql into a variable called rslt_rec_char.Hardness and if there is a space before the number (seems to be only problem) I need to remove it so the atof function will work. Can someone help me make changes to the code below to do this? Thanks. The int is_double just looks for decimal point and the function is posted below also.

    879         if (is_double(rslt_rec_char.Hardness))
    880             rslt_rec.Hardness = atof(rslt_rec_char.Hardness);
    881         else if (!strcmp(rslt_rec_char.Hardness,"")) 
    882             rslt_rec.Hardness = 0.0;
    883         else
    884         {
    885             rslt_rec.Hardness = 0.0;
    886             sprintf(jnl.mesg, "ERROR: CIN %s. Hardness test value invalid - \"%s\".\n"
    887                 "Hardness in test record %s not recorded!",
    888                 rslt_rec_char.CIN, rslt_rec_char.Hardness, rslt_rec_char.ResultsID);
    889             log_it(logfile,jnl);
    890             send_email(db_nm,"Met lab test upload error",jnl.mesg);
    891         }

   1421 int
   1422 is_double(char s[])
   1423 {
   1424     int index, decimal_point_found = 0;
   1425
   1426     if (!strcmp(s,"")) return 0; 
   1427
   1428     for (NULL; *s && isspace(*s); s++);
   1429     if (s[0] == '-') s++;
   1430
   1431     for (index = 0; index < strlen(s); index++)
   1432     {
   1433         if (s[index] == '.') decimal_point_found++;
   1434         else if (!isdigit(s[index])) return 0;
   1435     }
   1436
   1437     return ((decimal_point_found <= 1) ? 1 : 0);
   1438 }

[Dino]

char * first_nonblank = rslt_rec_char.Hardness ; 
while (*first_nonblank) { 
   if ( isspace(*first_nonblank) ) first_nonblank++ ; 
   else break ; 
}

then use first_nonblank inside the atof() function.

[matsp]

Surely this:

     for (NULL; *s && isspace(*s); s++);

is much clearer as:

     while(*s && isspace(*s))
          s++;

If nothing else, you can certainly remove the NULL before the first semicolon.

Also, you isdigit doesn't allow the

E{,+,-}[0-9]*

format of floating point.

--
Mats

[cjohnman]

Thanks for pointing out some improvements for my existing code. I will look into making those changes. I plugged the code above in this morning and it works but I am seeing the space in my printf and that concerns me. I don’t think the space is being removed. I copied the code below and placed the results of the printf below the code. Any ideas why I see the output like this. Before passing the string I have to remove that space. Also I am wondering what I can do if I happen to get a string with more than one whitespace. Couldn’t that cause a memory leak with this while loop?

     88     char hardness[256];

     89     char *first_nonblank;

     90     double hardness2;

     91

     92     strcpy(hardness,"23.345");

     93     first_nonblank = hardness;

     94

     95     while (*first_nonblank)

     96     {

     97     if (isspace(*first_nonblank))

     98     first_nonblank++;

     99     else break;

    100     }

    101

    102     hardness2 = atof(hardness);

    103

    104     printf("%s\n", hardness);

    105      

              /* Print again this time with space*/

    106     strcpy(hardness," 23.345");

    107     first_nonblank = hardness;

    108

    109     while (*first_nonblank)

    110     {

    111     if (isspace(*first_nonblank))

    112     first_nonblank++;

    113     else break;

    114     }

    115

    116     hardness2 = atof(hardness);

    117

    118     printf("%s\n", hardness);

Output:

23.345

(space)23.345

[Dino]

Yes, you have to print the string pointed to by first_nonblank to see the space removed. It really not physically "removed", it is just not part of the new string pointed to by first_nonblank, which is what you need for atof().

[cjohnman]

    char hardness[256];
    char *first_nonblank;
    double hardness2;

    strcpy(hardness,"23.345");
    first_nonblank = hardness;

    while (*first_nonblank)
    {
    if (isspace(*first_nonblank))
    first_nonblank++;
    else break;
    }

    hardness2 = atof(first_nonblank);

    printf("%s\n", hardness2);

    strcpy(hardness," 23.345");
    first_nonblank = hardness;

    while (*first_nonblank)
    {
    if (isspace(*first_nonblank))
    first_nonblank++;
    else break;
    }

    hardness2 = atof(first_nonblank);

    printf("%s\n", hardness2);

[Dino]

hardness2 is a double, not a string.

[cjohnman]

The following works great thanks to Tod's help!

    char hardness[256];
    char *first_nonblank;
    double hardness2;

    strcpy(hardness,"23.345");
    first_nonblank = hardness;

    while (*first_nonblank)
    {
    if (isspace(*first_nonblank))
    first_nonblank++;
    else break;
    }

    hardness2 = atof(first_nonblank);

    printf("%f\n", hardness2);

    strcpy(hardness," 23.345");
    first_nonblank = hardness;

    while (*first_nonblank)
    {
    if (isspace(*first_nonblank))
    first_nonblank++;
    else break;
    }

    hardness2 = atof(first_nonblank);

    printf("%f\n", hardness2);

[laserlight]

Personally, I find this:

while (*first_nonblank)
{
if (isspace(*first_nonblank))
first_nonblank++;
else break;
}

easier to read and understand as:

while (*first_nonblank && isspace(*first_nonblank))
{
    first_nonblank++;
}

Also, since the null character is not a space, you could simplify that to:

while (isspace(*first_nonblank))
{
    first_nonblank++;
}

which is even more straightforward to read and understand.

[Dino]

Good simplification laserlight.

Todd

[cjohnman]

I plugged your simplified version of Todds code in and it worked great! Thanks for your feedback. If there was more than one space this would work and no worrys about memory leak right?

[matsp]

I plugged your simplified version of Todds code in and it worked great! Thanks for your feedback. If there was more than one space this would work and no worrys about memory leak right?

There are no memory allocations in the code posted here, so I don't see how it could leak anything.

--
Mats

[cjohnman]

I just realized I need to discard the first space if one exists but if more than one exists do some error handling. So I only want the value if no space exists or if one exists. Other than that break out of loop and do some error handling. Any one care to help me adjust the loop laserlight posted?

Thanks in advance.

[matsp]

My idea would be to add an additional variable, which is originally zero, then increment it within the loop, and if it's greater than one when the loop finishes, you've got an error.

--
Mats

[laserlight]

Actually, in that case I do not think you need a loop. If the first two characters are spaces, then there is an error. Else, if only the first character is a space, then you ignore it. Else, you can convert immediately.