Issue creating a string from file using strcat

**wormsworm** · 02-20-2008

I'm trying to read a column of random sized order numbers from a file and put them in one long string that will be used later. each order needs to be separated by a ",".

Ex:
000111222-1112233
002233-393900

Output:
Value=000111222-1112233,002233-393900

This is what i have so far, but it definitely is messed up... any help is greatly appreciated!

Code:

int i;
long file;
char longOrderID[300];

     /* Create a new file */
     if ((file = fopen(filename, "r" )) == NULL) {

          lr_output_message("Unable to create %s", filename);
          return -1;
     }

     strcpy(longOrderID, "Value=");

	 for(i=0;i<=2;i++){

	fscanf(file, "%s", longOrderID);
                strcat(longOrderID, file);
	strcat(longOrderID, ",");
                mktemp(longOrderID);

	i++;

                }

**zacs7** · 02-20-2008

Code:

     /* Create a new file */
     if ((file = fopen(filename, "r" )) == NULL) {

          lr_output_message("Unable to create &#37;s", filename);
          return -1;
     }

Doesn't create a new file, in-fact it will fail if the file doesn't exist.

Do you really think 'longOrderID' will be big enough to hold the entire file?

Do you mean turn a file such as:

1234567
5451213
1231231
1421241

Into, another file:
Value=1234567,5451213,1231231,1421241

Or you plan to not save 'Value' at all?

You might consider reading the lines as:

Code:

char line[256];

/* open file */

while(fgets(line, sizeof(line), file) != NULL)
{
    /* add line to 'Value' */    
}

That way it doesn't matter how many order id's are in the file.

**whiteflags** · 02-20-2008

What you are doing is using the result string to read input into the buffer, which is causing you to overwrite parts of what you want.

You could do this with minimal extra space if you are confident you have allocated enough memory. Here's one untested idea:

Code:

char longOrderID[300] = { '\0', };
char * p = longOrderID; /** position in longOrderID **/
char * nl = NULL;       /** find newline characters **/

size_t read, bufsiz;

strcpy( p, "Value=" );
bufsiz = sizeof longOrderID;
read = strlen( p );
p += read;
bufsiz -= read;

/** read in chunks: **/
while( bufsiz > 0 && fgets( p, bufsiz, file ) != NULL ) {
   if ( ( nl = strchr( p, '\n' ) ) != NULL )
      *nl = '\0';

   strcat( p, "," );
   read = strlen( p );
   p += read;
   bufsiz -= read;
}

That should be fairly straight forward, but I've been wrong before.

**wormsworm** · 02-21-2008

Thanks for the help so far!

Unfortunately, I keep getting a memory violation at the 'fgets' section (when using either of the two suggestions)

any more assistance would be much appreciated!

**vart** · 02-21-2008

Originally Posted by wormsworm

Thanks for the help so far!

Unfortunately, I keep getting a memory violation at the 'fgets' section (when using either of the two suggestions)

any more assistance would be much appreciated!

Show your current code

**wormsworm** · 02-21-2008

Sorry, this is what i have so far: (this is for a Loadrunner script, so some code with LR_ is made for that program)

This code does work except for finding the '/n' within this code
if ( ( nl = strchr( p, '\n' ) ) != NULL )
*nl = '\0';

I'm getting an error: "operands of = have illegal types `pointer to char' and `int'"

if i comment out the if statement, the code works, but there is a return after each order id (which i do not want)

Code:

Action() {

char *filename = "Inbound_OrderID_Copies.txt";
long file;
char longOrderID[30000] = { '\0', };
char * p = longOrderID; /** position in longOrderID **/
char * nl = NULL;       /** find newline characters **/

size_t read, bufsiz;

strcpy( p, "Value=" );
bufsiz = sizeof longOrderID;
read = strlen( p );
p += read;
bufsiz -= read;

/** read in chunks: **/
    if ((file = fopen(filename, "r")) == NULL ) {

          lr_error_message("Cannot open &#37;s", filename);
          return -1;
     }

while( bufsiz > 0 && fgets( p, bufsiz, file ) != NULL ) {
   if ( ( nl = strchr( p, '\n' ) ) != NULL )
     *nl = '\0';

   strcat( p, "," );
   read = strlen( p );
   p += read;
   bufsiz -= read;


	 lr_output_message("OrderID = %s", longOrderID);
}
	
     return 0; 

}

**vart** · 02-21-2008

file should be

FILE* file;
about your warning - check the include headers - probably you are missing several - this could be a reason for crash

**wormsworm** · 02-21-2008

vart, you are exactly correct! I'm using Loadrunner software which contains it's own header files and I needed to copy a "studio.h" from another program into Loadrunner.

That fixed the problem and the script is working perfectly!

Thank you very much "citizen" for the great assistance!

**Elysia** · 02-21-2008

Oh yes, give all your functions a return type. Always.
And try indenting a little better. If you need a little assistance, try this.

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Issue creating a string from file using strcat

Thanks for the suggestions, but getting memory violation

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