split string and remove substring

This is a discussion on split string and remove substring within the C Programming forums, part of the General Programming Boards category; I want to remove the character '$' and substring "%%&&**" from an input string S. The substring can occur many ...

  1. #1
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    Question split string and remove substring

    I want to remove the character '$' and substring "%%&&**" from an input string S. The substring can occur many times within S. I need to use a function that can split S into 2 substring Sleft and Sright, then call this function from main function to remove the substring and concatenate the Sleft and Sright into a new string call S2.

    Please help me!

  2. #2
    Registered User carrotcake1029's Avatar
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    strchr in conjunction with strcat would be a good bet.

    Otherwise, looping through the string on your own wouldn't be that difficult either. Both ways you will need to incorporate a loop.

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    sorry, I'm a newbie, I understand strchr and strcat, but I can't figure out how to loop the pointer. Here is what I understand so far

    Code:
    fgets(buf,250,s);                  //read file
         while (!feof(s))
         {  
              character=strchr(buf,"=");          
           sub=strstr(buf,"%%&&**");
    
           plength=strlen(sub);
           fgets(buf,250,s);
         }
             Remove1(s,p,sleft,sright)

  4. #4
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    If the substring that you want to remove can occur several times in the string, then you'll need to remove each instance, and concatenate the string back together again, inside the while loop, instead of outside it.

    So in the code sample that was linked to above, in red, you would need a call to remove and re-join the string, after every substring is found.

    I strongly recommend you take this step by step - not all at once. Get a small test string and assign a smaller substring or char you want to remove. Test it block of code, by block of code, for logical accuracy and for proper syntax.

    Except for the re-joining part, I would work in your test program, right from the code sample on the C reference site on that page. The pointer arithmetic is a little tricky. It's the pointer value returned by strchr(), minus the base address (first char's pointer address), of the string, minus one.

    Simple, but subtle, too.

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