location of the string - Accessing individual string from a pointer array

Question

I want to find a string inside another character array. I tried to compare it character by charcter. But I cannot access individual character, I need some help here.

code

#include <stdio.h>
#include "source.h"

int main()
{  
    char *str[] = {"one","two","three","four"};
    int index;    

    index= locate_string(str, 4, "one");
    printf("String one is in the position %d\n", index);

    return 0;
}

int locate_string(char **stringArray, int len, char * string)
{
    int count = 0;
    while(count <= len){
      int j = 0;
      char *temp = (*stringArray)[count];

      while(j < len){
        if(temp == string[j]){
            j++;                
        }
      }
      if(j == len-1){
        return count-j;
      }
    }
    return -1;
}

Thanks, for the help. I'm learning programming in C from last week.

while(count <= len){ should be while(count < len){. should use strcmp to compare strings — amdixon
– amdixon, Commented Sep 28, 2015 at 10:17

amdixon · Accepted Answer · 2015-09-28 10:37:33Z

1

fixes

iterate over count < len ( not <= len )

use strcmp to simplify string comparison ( thats what its there for )

increment counter count to correctly loop over string array

code

#include <stdio.h>

int main(void)
{  
  char *str[] = {"one","two","three","four"};
  int index;    

  index = locate_string(str, 4, "one");
  printf("String one is in the position %d\n", index);

  return 0;
}

int locate_string(char **stringArray, int len, char *string)
{
  int count = 0;
  while(count < len)
  {
    if(!strcmp(stringArray[count], string))
    {
      return count;
    }
    ++count;
  }
  return -1;
}

output

$ gcc -g test.c -o test
$ valgrind ./test
==12705== Memcheck, a memory error detector
==12705== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==12705== Using Valgrind-3.10.0.SVN and LibVEX; rerun with -h for copyright info
==12705== Command: ./test
==12705== 
String one is in the position 0
==12705== 
==12705== HEAP SUMMARY:
==12705==     in use at exit: 0 bytes in 0 blocks
==12705==   total heap usage: 0 allocs, 0 frees, 0 bytes allocated
==12705== 
==12705== All heap blocks were freed -- no leaks are possible
==12705== 
==12705== For counts of detected and suppressed errors, rerun with: -v
==12705== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

above is a sample run with valgrind to stop the leaks..

answered Sep 28, 2015 at 10:37

amdixon

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1 Comment

Mitty Over a year ago

Thanks. I accessed the strings in a wrong way. And thanks for the tips about valgrind. I'm accepting your answer.

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