Question

I an new in c programing so I am not understanding to work for the process.

I have a structure defined like following way.

struct codons
{
    char amino_acid[20], slc[20], dna_codon[40];
};

struct codons c1 = {"Isoleucine", "I", "ATT, ATC, ATA"};
struct codons c2 = {"Leucine", "L", "CTT, CTC, CTA, CTG, TTA, TTG"};

User has to input the string sequence. for example :

printf("Enter the sentence: ");
gets(str);

if user enters string like :

ATTCTGCTTTTA

Then I have to convert this string to 3char length strings like

ATT, CTG, CTT, etc.   

and then, I have to check if that this short string of 3 chars present in structure of not.

I dont have any idea how I can convert the string into 3char string length and check.
Can anyone suggest me something?

Answer 1

You could do something like below:

char* input_string = ...;

//check if user entered string that could be divided into 3 letters substrings
if (strlen(input_string) % 3 != 0)
  return;

while (*input_string != '\0')
{
   char string_3l[4] = {'\0'};
   strncpy(string_3l, input_string, 3);

   //check if string_3l is part of structure 
   if ((strstr(string_3l, c1.dna_codon) != NULL) || 
               (strstr(string_3l, c2.dna_codon) != NULL))
   {
        //YOU HAVE MATCH!
   }

   input_string += 3;
}

Of course you should check in both c1 and c2 structures.