Passing and returning strings from a function

I have a situation where I have to map a 3 letter code of Amino Acid to its 1 letter code. Like ALA=>A. So if I have 'ALA' in my array, it should match and print 'A'. The following is a snippet of the code I had written..its giving a segmentation fault...kindly help
***This is the full code**

Code:

char* dictionary_func(char*);

manin()
{
FILE *fp;
char amino[4];
char line[80];
char chain='0';
char chain1='1';
char code[1];
int i,j,k,count=0;
int chain_count=0;

fp=fopen("test.pdb","r");

    if(fp!=NULL)
    {

    while(fgets(line,80,fp )!=NULL)
    {
    
    if((line[0]=='A')&&(line[1]=='T')&&(line[2]=='O')&&(line[3]=='M'))
        {
        count++;
            chain=line[21];
            if(chain1!=chain)
            {
                if(chain==' ')
                    printf(">Sequence:\n");
                else{
                    chain_count++;
                    printf("\n>Chain %c \n",chain);;
                    }
            }
            chain1=chain;        
            for(i=17,j=0;i<=19,j<3;i++,j++)
            {
            
                amino[j]=line[i];
    
            }
            //printf("%s",amino);
           
            printf("%s",dictionary_func(amino));                 //This is the part giving the segmentation fault
            if(count%70==0)
                printf("\n");
        }
    
    }
    fclose(fp);

    }

}

char* dictionary_func(char*s)
{

   if(strcmp(s,"ALA")==0)
      {
          return ("A");
           }


}

Strings have a terminating null character at the end. If you want to use "ALA" you will need space for 4 characters, not 3.

Tried..didnt work

You are still getting a segfault? Or are you getting some errors? Post your revised code.
Give an example input when it segfaults. You need to have an else return in your function just in case ALA!=0

What include files are you including?

You may want to see about increasing your compiler warnings, these are the warnings I received when I compiled your code:

main.c||In function ‘main’:|
main.c|40|warning: left-hand operand of comma expression has no effect [-Wunused-value]|
main.c|15|warning: unused variable ‘k’ [-Wunused-variable]|
main.c|14|warning: unused variable ‘code’ [-Wunused-variable]|
main.c|9|warning: unused variable ‘fi’ [-Wunused-variable]|
main.c||In function ‘dictionary_func’:|
main.c|69|warning: control reaches end of non-void function [-Wreturn-type]|
||=== Build finished: 0 errors, 5 warnings ===|

Jim

Thank you so much ...that was the problem, I should have given the else condition.......its working fine now!!!

Don't forget about that first warning. It is telling you your for() statement is malformed.

Jim

oh..ok..thanks..i will try to find a way around it..