CODEWITHSUNDEEP
c++string
David Merinos
David Merinos

Reputation: 1295

My program is deleting a character from a string, how to avoid that?

I have this program that is supposed to find a string of 3 chars, say "abc" into a longer string say "aabccbd" and then replace the coincidence with another char (say 'd') into the original string. So. Given those strings the results would be:

  1. aabcabcd
  2. adabcd <<-- another iteration
  3. addd <<-- Final result

And I've written a few code lines that I believe solve the problem of replacing the given sequence (Still haven't programmed the displacing of chars). But the thing is that when I replace the sequence with the given char, the char that is before the sequence gets deleted. Example:

  1. aabcabcd
  2. dabcd <<-- Incorrect

What could possibly be wrong? Check my code please. The sequence is read from a .txt file with the following format:

a b c d <- Sequence and swapping character. (Sequence is always 3 chars long) abcdefakxoqp333 <- Complete string where I'm supposed to search for the sequence.

Code:
#include<stdio.h>
#include<iostream>
#include<stdlib.h>
#include<string.h>
using namespace std;
char* gen = new char[3];
char simp;
char dna[10001];

int main() {
    int len;
    //Reading file and assigning values.
    FILE *input = fopen("input.txt","rt");
    fscanf(input,"%c %c %c %c",&gen[0],&gen[1],&gen[2],&simp);
    fscanf(input,"%s",&dna);
    fclose(input);
    len = strlen(dna);
    //In this part dna has the 2nd line of input.txt
    for(int i=0;i<len;i++){
        cout << dna[i];
    }
    cout << endl;
    //Searching for coincidences.

    int dnaLen = len; //dna Lenght, this one will change over time.
    bool found=false;
    int index=0; //Index will be reseted as well when we make a change!!
    while(index<dnaLen-2) {
            cout << "Entering WHILE with index=" << index << "\n";
            cout << "Examining: " << dna[index] << dna[index+1] << dna[index+2] << endl;
        if(dna[index]=gen[0] && dna[index+1]==gen[1] && dna[index+2]==gen[2]){
            //Replace dna[index] for simp AND displace the dna array
            dna[index]=simp;
            for(int i=0;i<dnaLen;i++){
                cout << dna[i];
            }
            cout << endl;
            index =0;
            dnaLen=dnaLen-2;
        }
        index++;
    }
    return 0;
}

I know I can try with regex, the thing is I'm kind of restricted on the use of C++11. I also know I can use string::replace but what's wrong with this code? Thank you!

Upvotes: 1

Views: 88

Answers (1)

VitaliyG
VitaliyG

Reputation: 1857

This is not a comparison but assignment, replace = with ==

if(dna[index]=gen[0]...

Upvotes: 2

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