Showing posts with label pattern. Show all posts
Showing posts with label pattern. Show all posts

Monday 8 August 2016

Lab Program 2 String 15CSL38 Data Structures in C Lab

Lab Program 2:


Design, Develop and Implement a Program in C for the following operations on Strings
a. Read a main String (STR), a Pattern String (PAT) and a Replace String (REP)
b. Perform Pattern Matching Operation: Find and Replace all occurrences of PAT in STR with REP if PAT exists in STR.
c. Report suitable messages in case PAT does not exist in STR
Support the program with functions for each of the above operations. Don't use Built-in functions.

#include<stdio.h>
char str[50], pat[20], rep[20], ans[50];
int     c=0, m=0, i=0, j=0, k, flag=0;
void stringmatch()
{
                 while(str[c] !='\0')
                {
                                if(str[m] == pat[i])
                                {
                                                i++;
                                                m++;
                                                if(pat[i] == '\0')
                                                {             
                                                                flag = 1;
                                                                for(k=0; rep[k]!='\0'; k++, j++)
                                                                {
                                                                                ans[j] = rep[k];
                                                                }
                                                                i = 0;
                                                                c = m;
                                                }
                                }
                                else
                                {
                                                ans[j]= str[c];
                                                j++;
                                                c++;
                                                m=c;
                                                i=0;
                                }
                }
                ans[j]='\0';
}
void main()
{
                printf("\nEnter the main string:");
                gets(str);
                printf("\nEnter the pat string:");
                gets(pat);
                printf("\nEnter the replace string:");
                gets(rep);
                stringmatch();
                if(flag == 1)
                                printf("\nResultant string is %s", ans);
                else
                                printf("\nPattern string is not found");
}

Enter the main string:    hello aabhii howaab
Enter the pat string:        aab
Enter the replace string:                               klmno

Resultant string is: hello klmnohii howklmno





Method 2:

#include<stdio.h>
#include<string.h>
#include<stdlib.h>

char str[50], pat[50], rep[50];
int start = 0, patfound = 0;
int lasts, lastp, lastr;

void replacepattern()
{
            int i, j;
            lastr = strlen(rep)-2;
           
            if(lastp != lastr)
            {
                        printf("\nInvalid length of replace string");
                        exit(0);
            }
            else
            {
                        i = start;
                        for(j=0; j<=lastr; j++)
                        {
                                    str[i] = rep[j];
                                    i++;
                        }
            }
            return;
}

void findpattern()
{
            int i, j, inmatch;
            lasts = (strlen(str))-2;
            lastp = (strlen(pat))-2;
            int endmatch;

            for(endmatch = lastp; endmatch<=lasts; endmatch++, start++)
            {
                        if(str[endmatch] == pat[lastp])
                        {
                                    inmatch = start;
                                     j=0;
                                    while(j<lastp)
                                    {
                                                if(str[inmatch] == pat[j])
                                                {
                                                            inmatch++;
                                                            j++;
                                                }
                                                else
                                                {
                                                            break;
                                                }
                                    }
                                    if(j == lastp)
                                    {
                                                patfound = 1;
                                                replacepattern();
                                    }
                        }
            }
            return;
}

void main()
{
            printf("\nEnter the main string(STR): ");
            fgets(str, 50, stdin);

            printf("\nEnter the pattern to be matched(PAT): ");
            fgets(pat, 50, stdin);

            printf("\nEnter the string to be replaced(REP): ");
            fgets(rep, 50, stdin);

            printf("\nThe string before pattern match is:\n %s", str);

            findpattern();

            if(patfound == 0)
                        printf("\nThe pattern is not found in the main string");
            else
                        printf("\nThe string after pattern match and replace is: \n %s ",str);
            return;
}


 Output:


Case 1:

Enter the main string(STR):    Hello hii how are you hii

Enter the pattern to be matched(PAT): hii

Enter the string to be replaced(REP): xyz

The string before pattern match is:
 Hello hii how are you hii

The string after pattern match and replace is:
 Hello xyz how are you xyz




Case 2:

Enter the main string(STR): Hello hii how are you

Enter the pattern to be matched(PAT): abc

Enter the string to be replaced(REP): xyz

The string before pattern match is:
 Hello hii how are you

The pattern is not found in the main string



Also Credits to: 
Manoj Taleka  (manoj89biet@gmail.com)
Yashaswini Jogi (jogi.yash@gmail.com)