Thread: checking if a string contains a letter

  1. #1
    Registered User
    Join Date
    Apr 2003

    Unhappy checking if a string contains a letter

    I wrote this piece of code but I'm not satisfied at all with it. Could anyone provide me with a better and smarter code to do the trick ?
    thanks in advance
    #include   <stdio.h>
    #include   <ctype.h>
    int contains_a_letter(char * address)
    	int i;
    	int output;
    	output = 1;
    	for ( i=0;  address[i]!='\0'; i++ ) {
    						printf("address[i] : %d\n",address[i]);
            					if( isalpha( address[i] ) )
                				 	printf("  There is a letter \n");                
    					 	output = 0;
                       			 	printf("  There is no letter \n");	              
    int result;
    char address[32]="2574A4564G54";
    result = contains_a_letter(address);
    printf("result : %d\n", result);
    if (result == 0) {
    	printf("address contains a letter\n");
    else {
    	printf("address doest not contain a letter\n");
    return 0; 

  2. #2
    Registered User Codeplug's Avatar
    Join Date
    Mar 2003
    Instead of "output = 0;", do "return 0;"
    No point in looping through the rest of the string once you find an alpha.

    - make your parameter "const char *address", since you don't modify it
    - main() returns int, declare it (this is required in the latest C standard)
    - "char address[32]="2574A4564G54";" - don't need to declare the size since you are initializing it - but it doesn't hurt either.


  3. #3
    Confused Magos's Avatar
    Join Date
    Sep 2001
    bool ContainsLetter(const char* String)
       //Abort if no string is passed
       if(String == NULL) return false;
       while((*String) != '\0')
          if(isalpha(*String)) return true;
       return false;

    Give a man a fish and you feed him for a day.
    Teach a man to fish and you feed him for a lifetime.

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