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STRCAT problem

Discussion in 'C' started by Frusciante, Jul 4, 2007.

  1. Frusciante

    Frusciante New Member

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    Hi!
    I wanted to thank you a lot for the help given yesterday...
    It`s so great to have people so well prepared trying to help you!

    I have another problem: the bold line :
    strcat want a pointer as argument, but probably i'm mistaking it ... can anybody help me?

    Code:
    #include <stdio.h>
    #include <string.h>
    
    main ()
    {
    int i;
    char j;
    char *ip;
    
    for (i = 0; i < 10; i++)
        {
    	ip=&j;
          for (j = 0; j<3; j++)
    	  {
    		FILE *fp;
    		
          char filename[17] ;
    	  
          if      (i == 0) 
    		{
    		 	strcpy(filename, "injection-0");
    			if (j==0) strcat(filename,"_11.txt");
    			[B]else if (j==1) strcat (filename,*ip)[/B];
    			else if (j==2) strcat (filename,"_12.txt");
    		}
    if ((fp = fopen(filename, "w")) != NULL)
    		{
    			fprintf(fp, "mass_part    mass_flow_part   diam_part      accretion      surf_ID   cel_ID    temp           vel_abs        vel_nor        vx             vy             vz             Ax             Ay             Az             Angle		Wa		Wb		Wc		WEAR\n");
    			fclose(fp);
    		}
    	  }
        }
    }
    
    Edited by DaWei to add code tags. Please do this yourself, in future.
     
  2. DaWei

    DaWei New Member

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    ip is a pointer to a char, not to an array of char (a string), as required by strcat.

    You also have a potentially bad issue: unless you have a C99 compliant C compiler, you'll have problems if you declare variables down in the body of the code. For C code, put all your declarations at the top, before any runtime statements. Even if your compiler tolerates it, it isn't portable code. If you're writing C and compiling it as C++, that's not a Good Thang.

    On the issue of formatting, please put your code in code tags, hereafter. Read the "Before you make a query" thread. I'd also recommend paying a little more attention to your formatting. Be consistent with your indentation. If you're planning on being a professional, someone else is going to wind up maintaining your code. They might be big, muscular, and mean.
     
  3. Frusciante

    Frusciante New Member

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    Thanks for your advices DaWei!
    I will remember them! :)

    Is it possible to concatenate just an int to the char filename?

    In that case I would be safe...
     
  4. Frusciante

    Frusciante New Member

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    I got it...
    I can use sprintf

    PHP:
    sprintf(filename"injection-%1d_%1d.txt"i,j);
     
  5. DaWei

    DaWei New Member

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    Just as a reminder, move the red statements to where shown in blue. This is a scoping issue that will affect portability of C code. It's great in C++.
    Code:
    main ()
    {
    int i;
    char j;
    char *ip;
    [COLOR=Blue]FILE *fp;[/COLOR]
    [COLOR=Blue]char filename[17] ;[/COLOR]
    for (i = 0; i < 10; i++)
        {
    	ip=&j;
            for (j = 0; j<3; j++)
    	{
    	    [COLOR=Red]FILE *fp;[/COLOR]
                [COLOR=Red]char filename[17] ;[/COLOR]
    ...
    
     
  6. Frusciante

    Frusciante New Member

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    Good to know!
    :)
     

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