Ytukyg

I'm trying to find the best way to compare multiple strings in C.
Currently, I'm using strcmp(); function, but it's turning out to be too many if
statements. I was also using ternary operator but unfortunately for me, it doesn't help.
Is there any better solution?
Here is example code:

#include <stdio.h>

#include <stdlib.h>

#include <string.h>



int main()

{

    char command = "First Second Third";

    char * del = " ";

    char * token;

    char * strings[3];

    int n = 0;

    token = strtok(command, del);



    while (token != NULL){



        strings[n] = token;

        token = strtok(NULL, del);

        n++;

    }

    // Now, strings[0] = "First", strings[1] = "Second", and strings[2] = "Third"



    // Only examine strings[1] and strings[2] after we know strings[0] = "First".

    if (strcmp("First", strings[0]) == 0){

        //do something

        if (strcmp("Second", strings[1]) == 0){

            //do something

            if (strcmp("Third", strings[2]) == 0){

                //do something

                printf("CORRECT");

                //do something

            }

        }

    }



    return 0;

}

OP's code has some problems

• 
  

  while (token != NULL) has no limit to 3 loops. Code may attempt strings[3] = token;

  
  
  

  // while (token != NULL){
  
  while (n < 3 && token != NULL){
  
  

  
  


• 
  

  Code uses strings[0], strings[1], strings[2] without first insuring that many tokens were parsed.

  
  
  

  // strcmp("First", strings[0]) == 0
  
  (n > 0 && strcmp("First", strings[0]) == 0)
  
  

  
  



• Code saves a pointer to the original string. Once strtok() is call again, the prior token can be lost/changed.

The "best" way involves hashing the key and targets, yet that is a lot to explain here.

Alternative: With such a simple match needed as in OP's example, code could use "%n" to record the offset of the scan.

int n1 = 0, n2 = 0, n3 = 0;

sscanf(command, "First %n Second %n Third %n", &n1, &n2, &n3);



if (n1) {      // n1 is non-zero if scan matched "First"

    //do something

    if (n2) {  // n2 is non-zero if scan matched "First Second"

        //do something

        if (n3) {

            //do something

            printf("CORRECT");

            //do something

        }

    }

}

It looks like your if statements should be using strcmp() instead of the posted strtok(). Also, I think you are looking for something more like if ... else if ... else if ..., rather than nested if's.

Depending on the real program you're writing (vs. posted), you could also use a switch() based on the first character in the string to compare. It amounts to a crude hashing function. (you may want to learn more about hashing to adapt what you have to what you want).

EDIT:
Maybe this is what you're getting at:
.
.
.

    if (strcmp(strings[0], "cmdA") == 0)

        processCmdA(strings[1], strings[2]);

    else

    if (strcmp(strings[0], "cmdB") == 0)

        processCmdB(strings[1], strings[2]);

    else

    if (strcmp(strings[0], "cmdC") == 0)

        processCmdC(strings[1], strings[2]);

.

.

.

void processCmdA(char* optionA, char* inputFileName)

{

    if (strcmp(optionA, "parse") == 0)

        parseFile(inputFileName);

    else

    if (strcmp(optionA, "cksum") == 0)

        computeCheckSum(inputFileName);

    else

.

.

.

}



void parseFile(char* inputFileName)

{

    // do parse stuff

}

.

.

.