Thread: c code: split string || multiple/optional delimiters || memcpy - optimize

Hi devs,

I am writing a code to parse strings with genetic information. Data are clunky with randomness.
For example,

GENE1;GENE2
GENE21,GENE22
GENE12

I need name of each gene separately: GENE1, GENE2 and such. It is possible that there is no comma or ; in the string for instance, in GENE12.

strtok isn't helpful in this kind of situation that is why I worked on this piece of code.

I wrote code below, it works, but I think it is error prone.

Code:

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


//  gcc -Wpedantic -Wextra -Wall hello.c -o print
int main(int argc, char *argv[])
{


    //char tab[] = "hello;morgan;chase;capital,house";
    char tab[] = "hello,discover"; //split this string
//    char tab[] = "hello"; //split this string
    printf("we have value as tab %s\n", tab);


    int itr; //use to iterate
    int str_len = strlen(tab); //use for length variable of string


    int temp_itr = 0; //use to keep value of itr when needed
    char temp_gene[200]; //store value in this of sub-string


    for (itr = 0; itr < str_len; itr++)
    {
        if (tab[itr] == ',' || tab[itr] == ';')
        {
            if (temp_itr == 0)
            {
                //if no comma or ; has been found 
                memcpy(temp_gene, tab + temp_itr, itr - temp_itr);
            }
            else
            {
                memcpy(temp_gene, tab + temp_itr + 1, itr - temp_itr - 1);
            }


            temp_gene[itr - temp_itr] = '\0'; //end with null character
            printf("split wise is %s\n", temp_gene);
            temp_itr = itr;
        }
        temp_gene[0] = '\0'; //set first char null
    }


    temp_gene[0] = '\0'; //set first char null
    
    if (temp_itr == 0)
    {
        //if no comma or ; has been found 
        memcpy(temp_gene, tab + temp_itr, str_len - temp_itr);
        temp_gene[str_len - temp_itr] = '\0'; //end with null character
    }
    else
    {
        //if we already had temp_itr initiated and string has , or ;
        memcpy(temp_gene, tab + temp_itr + 1, str_len - temp_itr);
        temp_gene[str_len - temp_itr] = '\0'; //end with null character
    }


    printf("final split wise is %s\n", temp_gene);


    return 0;
}

I find this code a little make-shift.

I would like to improve this than have multiple if checks. For instance, if (temp_itr == 0) in the end, if no comma or ; is found.

Thank you.

GENE1;GENE2
GENE21,GENE22
GENE12

I need name of each gene separately: GENE1, GENE2 and such. It is possible that there is no comma or ; in the string for instance, in GENE12.

Code:

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

char gene[128][256], genecount = 0;

void splitgenes( char *string ) {    
  int which = 0, count = 0;
  for (int i=0; i<strlen(string);i++) {
    if ( string[i] == ';' || string[i] == ',' || string[i] == '\n' ) {
      gene[which][count++] = '\0';
      which ++; count = 0;
    } else {
      gene[which][count++] = string[i];
    }
  } 
  gene[which][count++] = '\0';
  genecount = which;
}

int main( int argc, char *argv[] ) {      
  
    char genestring[] = "GENE1;GENE2\nGENE21,GENE22\nGENE12";


    splitgenes( genestring );    


    for (int i=0; i<=genecount; i++) {
        printf( "%s, ", gene[i] );
    }

    printf( "\n" );
    return 0;
}

> strtok isn't helpful in this kind of situation that is why I worked on this piece of code.
How so?

You can pass multiple tokens to strtok.

Code:

#include <stdio.h>
#include <string.h>
int main ( ) {
    char tab[] = "hello;morgan;chase;capital,house";
    const char *sep = ";,";
    for ( char *p = strtok(tab,sep) ; p != NULL ; p = strtok(NULL,sep) ) {
        printf("Got %s\n", p);
    }
}

C++ Shell

Got hello
Got morgan
Got chase
Got capital
Got house