I have tried all possible ways. I think there is some logical error in the function findlink()
The purpose of this function is to find and return a pattern from the argument abc.
For example, if abc is "Hello,My name is **Lorem ipsum sit amet ** and I am a student.", then findlink will return "Lorem ipsum sit amet". i.e. it returns the text between double asterisk. But due to some reason I am getting segmentation fault, though I have debugged and figured out that the fault is concerned with this function only, but I am unable to discover why.
char *findlink(char *abc)
{
if(abc==NULL)
return NULL;
cout<<"Findlink called for : "<<abc<<endl;
int i=0,flag=0,flag1=0,len=0;
char *link;
for(i=0;i<strlen(abc)-1;i++)
{
if(abc[i]=='*' && abc[i+1]=='*' && flag==0)
{
flag=1;
i+=2;
}
if(abc[i]=='*' && abc[i+1]=='*' && flag==1)
{
flag=0;
flag1=1;
i+=2;
}
if(flag==1 && flag1!=1)
link[len++]=abc[i];
if(flag1==1)
{
link[len++]='\0';
cout<<"Returning "<<link<<endl;
return link;
}
}
cout<<"Returning NULL\n";
return NULL;
}
.
Following is the full code for reference.
#include<iostream>
#include<fstream>
#include<string.h>
#include<stdio.h>
using namespace std;
ifstream infile;
ofstream outfile;
struct queue
{
struct node *front;
struct node *rear;
};
struct queue* createqueue()
{
struct queue *temp=new queue;
temp->front=NULL;
temp->rear=NULL;
return temp;
}
struct node
{
struct node *next;
char *value;
};
struct node * createnode(char *val)
{
struct node *new1=new node;
new1->next=NULL;
new1->value=val;
return new1;
}
struct queue *push(char *val,struct queue *queue1)
{
struct node *new1=createnode(val);
if(queue1->front==NULL && queue1->rear==NULL)
{
queue1->front=queue1->rear=new node;
queue1->rear=new1;
queue1->front=new1;
}
else
{
queue1->rear->next=new node;
queue1->rear->next=new1;
queue1->rear=queue1->rear->next;
}
return queue1;
}
struct queue *push(string val,struct queue *queue1) //overloaded function push for string arguments
{
char* cstr = new char[val.length() +1];
strcpy(cstr, val.c_str());
queue1=push(cstr,queue1);
return queue1;
};
struct queue *pop(struct queue *queue1)
{
struct node *temp=new node;
if(queue1->front==NULL)
return NULL;
else if(queue1->front==queue1->rear)
{
temp=queue1->front;
queue1->front=NULL;
queue1->rear=NULL;
cout<<"POP: Poping: "<<temp->value<<endl;
return queue1;
}
else
{
temp=queue1->front;
queue1->front=queue1->front->next;
cout<<"POP: Poping: "<<temp->value<<endl;
return queue1;
}
}
struct queue *scanitall(struct queue *queue1) //reads the contents from outputproject.txt and pushes all the contents in a queue
{
string line;
infile.open("outputproject.txt");
while(getline(infile,line))
{
char *line1=new char[line.length()+1];
strcpy(line1,line.c_str());
queue1=push(line1,queue1);
}
infile.close();
return queue1;
}
int search(struct queue* queue1,char *val) //returns 1 if val found in queue1 else 0
{
//cout<<"SEARCH called\n";
if(queue1->front==NULL || queue1->rear==NULL)
return 0;
struct node *temp=new node;
temp=queue1->front;
while(temp)
{
if(strcmp(temp->value,val)==0)
return 1;
temp=temp->next;
}
return 0;
}
char *findlink(char *abc)
{
if(abc==NULL)
return NULL;
cout<<"Findlink called for : "<<abc<<endl;
int i=0,flag=0,flag1=0,len=0;
char *link;
for(i=0;i<strlen(abc)-1;i++)
{
if(abc[i]=='*' && abc[i+1]=='*' && flag==0)
{
flag=1;
i+=2;
}
if(abc[i]=='*' && abc[i+1]=='*' && flag==1)
{
flag=0;
flag1=1;
i+=2;
}
if(flag==1 && flag1!=1)
link[len++]=abc[i];
if(flag1==1)
{
link[len++]='\0';
cout<<"Returning "<<link<<endl;
return link;
}
}
cout<<"Returning NULL\n";
return NULL;
}
struct queue *processit(struct queue *queue1,char *abc) //identifies link text in inputproject.txt
{
//cout<<"PROCESSIT called\n";
ofstream outfile;
outfile.open("outputproject.txt",ios::app);
if(!outfile)
cout<<"PROCESSIT: Error file not opened!\n";
char *link;
link=findlink(abc);
if(link)
cout<<"Caught: "<<link<<endl;
if(link)
if(search(queue1,link)==0)
{
cout<<"^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n";
outfile<<link<<endl;
queue1=push(link,queue1);
}
outfile.close();
return queue1;
}
void openallfiles(struct queue *queue1)
{
if(!queue1->rear)
cout<<"Queue Empty\n";
else
{
struct node *temp=new node;
temp=queue1->front;
string line;
while(temp)
{
ifstream infile;
infile.open(temp->value);
if(!infile)
{
cout<<"openallfiles:File not opened\n";
return;
}
while(getline(infile,line))
{
cout<<line<<endl;
}
infile.close();
if(temp)
temp=temp->next;
}
}
}/*
struct queue *findlinks(struct queue *crawl1,ifstream infile)
{
}
crawl(struct queue *crawl1)
{
ifstream infile1,infile2;
infile1.open("inputproject.txt");
crawl1=findlinks(crawl1,infile1);
}*/
void display(struct queue *queue1)
{
if(queue1->front)
{
struct node *temp=queue1->front;
while(temp)
{
cout<<"data:"<<temp->value<<endl;
temp=temp->next;
}
}
else{
cout<<"Sorry queue empty\n";
}
}
int main()
{
struct queue *queue1=createqueue();
struct queue *crawl1=createqueue();
queue1=scanitall(queue1); //push all contents of outputproject.txt in a queue
display(queue1);
//cout<<"Poping:\n";
/*while(queue1->rear)
queue1=pop(queue1);*/
string line;
char *line1;
infile.open("inputproject.txt");
while(getline(infile,line))
{
line1=new char[line.length()+1];
strcpy(line1,line.c_str());
queue1=processit(queue1,line1);
}
infile.close();
openallfiles(queue1);
return 0;
}
strncpyuntil you're read and understood its documentation. It is not a "safe" dropin replacement forstrcpy. If your source string is too long,strncpywill postpone the buffer overrun; it won't prevent it.