Navigating a character string array from pointers

This is a discussion on Navigating a character string array from pointers within the C Programming forums, part of the General Programming Boards category; This program loads 6 words into the array "keywords," then segfaults for some reason. Why does it do this? Code: ...

  1. #1
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    Navigating a character string array from pointers

    This program loads 6 words into the array "keywords," then segfaults for some reason. Why does it do this?


    Code:
    #include<stdlib.h>
    
    int main()
    {
    	char** keywords = (char**) calloc(20, sizeof(char));
    	int i = 0;
    	for (i = 0; i < 20; i++)
    		keywords[i] = (char*) calloc(80, sizeof(char));
    	char string[] =
    	{ "Holy cow omg hey haha wow oh jeeze louise lolz." };
    	char* p = NULL;
    	char* c = string;
    	int n = 0;
    
    	p = *(keywords + 0);
    	while (*c)
    	{
    
    		while (!isspace(*c) && *c)
    		{
    			*p++ = *c++;
    		}
    		*p = '\0';
    		if (!*c)
    			break;
    		c++;
    		n++;
    		p = *(keywords + n);
    		printf("%d\r\n", n);
    	}
    
    	for (n = 0; n < 10; n++)
    		printf("%s\r\n", keywords[n]);
    
    	free(keywords);
    	return 0;
    }
    Last edited by Boxknife; 04-16-2009 at 01:17 PM.

  2. #2
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    sorry
    Last edited by xmariux; 04-16-2009 at 01:48 PM.

  3. #3
    C++ Witch laserlight's Avatar
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    Better yet, change it to:
    Code:
    char** keywords = calloc(20, sizeof(*keywords));
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  4. #4
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    Quote Originally Posted by laserlight View Post
    Better yet, change it to:
    Code:
    char** keywords = calloc(20, sizeof(*keywords));
    This fixes the problem. Thanks!

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