Thread: need some help with Segmentation fault

This program is a new assignment for array and string, however the program shows segmentation error after first execution.

it says Segmentation fault.
i check the out put from the function check.
it print quiet normal.

i just spent 6 hour straight in the lab to fix the error.
however it is Friday , i can not get any help from TA.
If you guy can spare some time , it will be really appreciated.

Code:

#include <stdio.h>
#include <math.h>
#include<string.h>     
#include<stdbool.h>
#include<malloc.h>
int main(void)
{


  void record(char *response,char *guess, int NOG,int length,char **matrix);
  void check(char *key, char  *guess,char *response,int length);


  int t;
    
 




  printf("Enter the pattern length");
  int length;
  scanf("%d",&length);


  printf("Enter the number of guesses");
  int limit;
  scanf("%d",&limit);


  char *response; 
  response=(char *)malloc((length+1)*sizeof(char*));




  char guess[length];


 
 
  printf("Input the key pattern with no spaces:");
  char key[length+1];
  scanf("%s",key);


  int NOG=0;
  //response to generate the bww thing


  char **matrix;//for printing the result
matrix=(char **)malloc(2*limit*sizeof(char*));
 
for(t=0;t<limit;t++)
  matrix[t]=(char *)malloc((length*2+1)*sizeof(char));
                 
//making 2 dimentional array 'matrix'






 int j,w,k,g,c;


do


    {  printf("Input a guess pattern with no space:");
      
      scanf("%s",guess);
    
      check(key,guess,response,length);
  int counts;
  counts=0;
 
  for(j=0;j<length;j++)
    {matrix[NOG][j]=response[j];
     
      }
  matrix[NOG][j]=' ';
  
  for(k=length+1;k<length*2+1;k++)
    {matrix[NOG][k]=guess[k-length-1];
      
        }


  
  for(w=0;w<NOG+1;w++)
    {
    printf("%d: ",w+1);
    for(g=0;g<length*2+1;g++)
      {printf("%c",matrix[w][g]);
      }
 
    printf("\n");
    }








    NOG++;


    }
 while(strcmp(guess,key) && NOG!=limit);
 return 0;
    
}




















void check(char *key, char  *guess,char *response,int length)


  {
    int j,k,n,m,t,z,x,w,i;
    k=0;
   
  int counts=0;
  bool *badj;
for(t=0;t<length;t++)
  badj[t]=(bool *)malloc((length)*sizeof(bool));
 for(n=0;n<length;n++)
   badj[n]=1;
 


bool *bads;
 for(w=0;w<length;w++)
   bads[w]=(bool *)malloc((length)*sizeof(bool));




 for(z=0;z<length;z++)
   bads[z]=1;


    for(x=0;x<length;x++)
      {if(key[x]==guess[x])
      { response[k]='b';counts++;
                bads[x]=0;
                k++;
      }
      }
 










    








    for(i=0;i<length;i++)
      {  if(bads[i]==0)
    continue;




    for(j=0;j<length;j++)
    {if(badj[j]==0)
        {continue;}
      
      else if(key[i]==guess[j])
        {response[k]='w';counts++;
          badj[j]=0;
          k++;


          }
    }
      }
   for(m=counts;m<length;m++)
     {response[k]='.';k++;}
   response[k]='\0';
   printf("%s",response);
  }

well it is 2 AM right now just cant sleep before this program works

thank you for your reply Salem.
Really helps me a lot
i made some big changes on my code

Code:

bool *badj=null;

bool *bads=null;

As you mentioned about my point error.
i believe there are serial problem like this in my code

Code:

 char *response;
char **matrix;
char key[length+1] ;

are those considered to be mistakes?
if not what is the differenence between them and

Code:

bool* bads

TA always warm us about the string and array, but i still don not understand what is the difference between those 2
and the '0\' charactor at the end of the string,
do i have to do this every time after reading the input in? if not what kind of condition do i have to worry about string?

Code:

response[k] = '\0';

and can i do this to the string after user input the guess? when the string guess already has value inside. or do i have to use scanf("c")with for loop to scanf it seperately?

Code:

 printf("Input a guess pattern with no space:");    scanf("%s", guess);

if it is now legal, please share some thoughts about how to solve it.

i am really new to string, forgive me for asking silly questions
thank you

Originally Posted by zhangz64

i made some big changes on my code

Code:

bool *badj=null;
bool *bads=null;

That won't help (BTW: the macro is written NULL (all caps); C is case sensitive).

But could you please explain what do you want to achieve with these lines?

Code:

bool *badj;
for (t = 0; t < length; t++)
    badj[t] = (bool *) malloc((length) * sizeof(bool));
for (n = 0; n < length; n++)
    badj[n] = 1;
  
bool *bads;
for (w = 0; w < length; w++)
    bads[w] = (bool *) malloc((length) * sizeof(bool));
for (z = 0; z < length; z++)
    bads[z] = 1;

Originally Posted by zhangz64

Code:

 char *response;
char **matrix;
char key[length+1] ;

are those considered to be mistakes?

Depends on what you want to do with these variables.

Originally Posted by zhangz64

TA always warm us about the string and array, but i still don not understand what is the difference between those 2
and the '0\' charactor at the end of the string,

An array is a container which holds a defined number of objects of the same type.
A string in C is an array of type char terminated by the null character ('\0').

Originally Posted by zhangz64

do i have to do this every time after reading the input in? if not what kind of condition do i have to worry about string?

Code:

response[k] = '\0';

and can i do this to the string after user input the guess? when the string guess already has value inside. or do i have to use scanf("c")with for loop to scanf it seperately?
[code] printf("Input a guess pattern with no space:"); scanf("%s", guess);

scanf("%s", guess) adds the null character to the input, thus you don't need to add it yourself. If "guess" contains already something it will be overwritten.
If you read the input character by character, then you would have to add the null character.

Bye, Andreas