Thread: A little help here

I've always had this "thing" for the C programming language but because I was never able to validate user input with it, I went with C++ lol. Anyway, I've decided to give it another go, especially now that I am learning about the Win32 API and I want you guys to help me with something. I wrote this program in C++ (it is not completed yet but is a perfect example of what I want to accomplish in C) and I was wondering if someone could write a C version of it. Here's my program:

Code:

#include <iostream>
#include <string>
#include <sstream>
#include <vector>

bool validate_number_of_names(const std::string &);
bool validate_name(const std::string &);
bool validate_sort_type(const std::string &);
bool length_and_spaces(const std::string &);

int main()
{
    int number_of_names;
    std::string user_input;
    std::string name;
    std::vector<std::string> all_names;
    std::string sort_type;
    
    do{
        std::cout << "Number of names: ";
        std::getline(std::cin, user_input);
    }while(!validate_number_of_names(user_input));
    
    system("cls");
    
    std::istringstream iss(user_input);
    iss >> number_of_names;
    
    std::cout << "Now, start inputing the names. They have to be in the format\n"
              << "\"last, first, age\" with no spaces and the name string cannot\n"
              << "exceed 40 characters.\n\n";
              
    while(number_of_names != 0){
        do{
            std::cout << "Name: (" << number_of_names << " left) ";
            std::getline(std::cin, name);
        }while(!validate_name(name));
        
        all_names.push_back(name);
        
        number_of_names--;
    }
    
    do{
        std::cout << "\nThe names can be sorted by either last, first or age. How\n"
                     "would you like them to be sorted? ";
                     
        std::getline(std::cin, sort_type);
    }while(!validate_sort_type(sort_type));
              
    std::cin.get();
    
    return 0;
}

bool validate_number_of_names(const std::string &user_input)
{
     int number_of_names;
     int length_of_user_input;
     
     length_of_user_input = user_input.length();
     
     for(int i = 0; i != length_of_user_input; i++){
         if(!isdigit(user_input[i])){
             std::cout << "Invalid entry.\n\n";
             return false;
         }
     }
     
     std::istringstream iss(user_input);
     iss >> number_of_names;
     
     if(number_of_names > 100){
         std::cout << "Number of names must be between 1 and 100.\n\n";
         return false;
     }
     
     return true;
}

bool validate_name(const std::string &name)
{
     int i;
     int comma;
     int result;
     int second_comma;
     int comma_count = 0;
     int number_of_characters;
     std::string age;
     std::string last_name;
     std::string first_name;
     std::string last_and_first_names;
     
     if(!length_and_spaces(name))
         return false;
         
     number_of_characters = name.length();
         
     for(i = 0; i != number_of_characters; i++){
         if(name[i] == ','){
             comma_count++;
         }
     }
     
     if((comma_count < 2) || (comma_count > 2)){
         std::cout << "Invalid entry.\n\n";
         return false;
     }
         
     second_comma = name.find_first_of(',', name.find_first_of(',') + 1);
     
     last_and_first_names = name.substr(0, second_comma);
     
     comma = last_and_first_names.find_first_of(',');
     
     last_name = last_and_first_names.substr(0, comma);
     
     first_name = last_and_first_names.substr(comma + 1);
     
     age = name.substr(name.rfind(',') + 1);
     
     if(!length_and_spaces(last_name))
         return false;
         
     if(!length_and_spaces(first_name))
         return false;
         
     if(!length_and_spaces(age))
         return false;
         
     for(int i = 0; i != number_of_characters; i++){
         if(last_and_first_names[i] != ','){
             if(!isalpha(last_and_first_names[i])){
                 std::cout << "Invalid entry.\n\n";
                 return false;
             }
             
             return true;
         }
     }
         
     return true;
}  
     
bool validate_sort_type(const std::string &sort_type)
{         
     if((sort_type != "last") && (sort_type != "first") && (sort_type != "age")){
         std::cout << "Invalid entry.\n";
         return false;
     }
     
     return true;
}

bool length_and_spaces(const std::string &foo)
{
     int number_of_characters;
     
     number_of_characters = foo.length();
     
     if(number_of_characters == 0){
         std::cout << "Invalid entry.\n\n";
         return false;
     }
     
     for(int i = 0; i != number_of_characters; i++){
         if(isspace(foo[i])){
             std::cout << "Invalid entry.\n\n";
             return false;
         }
     }
     
     return true;
}

Thanks.

Thanks guys. Thinking about it now, I was kinda silly but now I'll at least try and come back here when I run into problems.

You're right Dave, I learn something every 5 minutes hanging out here! Do you guys like my new programming style?

Code:

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

// Boolean enumerator
typedef enum
{
  false,
  true
} bool;

// MAIN -- START
int main (void)
{
  // b1 is the first boolean value
  // b2 is the second boolean value
  bool b1 = true, b2 = false;

  // Check if the first boolean value is correct
  if (b1)
    puts ("Good!");
  else
    puts ("Bad!");

  // Check if the second boolean value is correct
  if (!b2)
    puts ("Good!");
  else
    puts ("Bad!");

  return 0;
}

Here's my first try:

Code:

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

int validate_number_of_names(const char[]);

int main()
{
    char number_of_names[4];

    do{
        printf("Number of names: ");
        fgets(number_of_names, sizeof(number_of_names), stdin);
    }while(validate_number_of_names(number_of_names) == 1);

    return 0;
}

int validate_number_of_names(const char number_of_names[])
{
    int i;
    int length_of_user_input;

    length_of_user_input = strlen(number_of_names);

    for(i = 0; i != length_of_user_input; i++){
        if(!isdigit(number_of_names[i])){
            printf("Invalid entry.\n\n");
            return 1;
        }
    }

    return 0;
}

The problem is, even if I input a valid numerical character, I get the error message. I think this is happening because the string is terminated with a \0 or \n, not sure which one though. Can somebody tell me how to get around this? Thanks.

Ok, this is what I have now:

Code:

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

int validate_number_of_names(const char *);

int main()
{
    char number_of_names[4];

    do{
        printf("Number of names: ");
        fgets(number_of_names, sizeof(number_of_names), stdin);
        number_of_names[strlen(number_of_names) - 1] = '\0';
    }while(validate_number_of_names(number_of_names) == 1);

    return 0;
}

int validate_number_of_names(const char *number_of_names)
{
    int i;

    if(number_of_names[0] == '\0'){
        printf("Invalid entry.\n\n");
        return 1;
    }

    for(i = 0; i != strlen(number_of_names); i++){
        if(!isdigit(number_of_names[i])){
            printf("Invalid entry.\n\n");
            return 1;
        }
    }

    return 0;
}

If I type 876t, for example, the program accepts the input, and that is not good. If I type uu8, things get even worse:

Code:

Number of names: uu8
Invalid entry.

Number of names: Invalid entry.

Number of names:

What is wrong now?

fgets() sucks up the '\n' character when you hit enter from the last fgets(). You want a sponge to suck up that '\n'! And I've got the code to fix that puppie up!

Code:

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

int validate_number_of_names(const char *);

int main()
{
    char number_of_names[4];
    int c;

    do{
        printf("Number of names: ");
        fgets(number_of_names, sizeof(number_of_names), stdin);
        while((c=getchar()) != EOF && c != '\n');
        number_of_names[strlen(number_of_names) - 1] = '\0';
    }while(validate_number_of_names(number_of_names) == 1);

    return 0;
}

int validate_number_of_names(const char *number_of_names)
{
    int i;

    if(number_of_names[0] == '\0'){
        printf("Invalid entry.\n\n");
        return 1;
    }

    for(i = 0; i != strlen(number_of_names); i++){
        if(!isdigit(number_of_names[i])){
            printf("Invalid entry.\n\n");
            return 1;
        }
    }

    return 0;
}

I'm afraid the changes you made didn't fix the problems. Instead, it added some more
I had to hit enter twice in order to get the my input into the program and things like 876t were still being accepted.

fgets only receives 3 characters.
You could type:
9279837496297634
And you only get "927".

You could type:
827iuusdflnsclhLKHJLKHERB
And you could only get:
"827"

fgets() has to ignore the rest of the characters because it only gets the amount that you asked for (3) characters + '\0' at the end.

Code:

while((c=getchar()) != EOF && c != '\n');
/* wont work because fgets() recieves the '\n' 
    try this calling this function after using fgets() */

void flush_newline(char *swap)
{
  char ch;
  int i;
  for(i=0;i<sizeof(swap);i++){
    ch = swap[i];
    if(ch == '\n')
        swap[i] = '\0';
  } 
}