Pointers, Strings and functions in C

Question

I've missed a week of class in which they covered pointers but I haven't been able to get the notes from class but my HW is due and I still don't understand how to use pointers to pass strings from function to function... below is my code in which I realize the pointers are beyond messed up but I've tried to read other forums but just get lost. Any help is appreciated.

#include <stdio.h>

char* returnInPlace(char);
int palindrom(char, char );

main(void)
{
  char newString[20];

  printf("Enter a string: ");
  scanf("%s",&newString);

  char flippedString[20]=reverseInPlace(newString);
  int palCheck= palindrome(newString, flippedString);

  if (palCheck==0)
    printf("\n\tThe reverse string is %s, so we don't have a palindrome.", flippedString);
  else
    printf("\n\tThe reverse string is %s, so we do have a palindrome.", flippedString);

}

char* reverseInPlace(char newString)
{
  int iterator;
  char flipped[20];
  char *ptr1;
  for(iterator=0;iterator<20;iterator++)
  {
    flipped[iterator]=firstString[19-iterator];
  }
  ptr1=flipped[];
  return *ptr1;
}

int palindrome(char newString, char flippedString)
{
  int iterator;
  int palCheck=1;
  for(iterator=0;iterator<20;iterator++)
  {
     if (firstString[iterator]==secondString[iterator])
      continue;
     else
     {
       palCheck=0;
       break;      
     }  
  }
  return palCheck;
}

what problems you are facing with this code? BTW main(void) should be int main(void) — Sourav Ghosh
– Sourav Ghosh, Commented Mar 20, 2015 at 13:24
return *ptr; means: return the value on the address that ptr contains. — moffeltje
– moffeltje, Commented Mar 20, 2015 at 13:29

Sourav Ghosh · Accepted Answer · 2015-03-20 13:33:43Z

1

Problem 1

In char* reverseInPlace(char newString), you're using

return *ptr1;

which is wrong. What you may want is

return ptr1;

Problem 2

ptr1=flipped[];

is wrong. Here, you're assigning the base address of a local variable flipped and returning that value. flipped will cease to exist after reverseInPlace() finishes execution. You need to use dynamic memory allocation.

Problem 3

char flippedString[20]=reverseInPlace(newString);

is wrong. You cannot assign an array with = unless as initialization at time of definition.

Problem 4

char* reverseInPlace(char newString)

this function definition looks wrong by seeing the way it is being called. Maybe what you want is

char* reverseInPlace(char* newString)

instead.

......and maybe many more. Strongly suggest to read some good book about Pointers and C basics before jumping into writing code.

edited Mar 20, 2015 at 13:33

answered Mar 20, 2015 at 13:26

Sourav Ghosh

135k17 gold badges192 silver badges271 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Evdzhan Mustafa Over a year ago

Capitalize the last p in 'problem 4' please ! :)

Adie Rector Over a year ago

for Problem 3, that is the first time I am declaring that variable so that's why I assigned it, am I not allowed to do so?

Collectives™ on Stack Overflow

Pointers, Strings and functions in C

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related