Question

Write a C program that loops and asks a user to enter a
an alphanumeric phone number and converts it to a numeric one.
No +1 at the beginning. 

You can put all code in one quiz1.c file 
or put all functions except main in phone.c and phone.h
and include it in quiz1.c 
Submit your *.c and .h files or zipped project
*/
#pragma warning (disable: 4996) //windows
#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#include <ctype.h>

enum { MaxLine = 255 };
bool isValid(char line[])
{
        //line is a string
        //returns true if line has 10 alnum characters
        //false otherwise
}

void toNumeric(char line[])
{
        //line is a string
        //use the switch statement we did in last lectures
        // (800) GOT - milk ; (800)GOT.milk, etc
        //convert letters to digits; leave rest as is.
}

void puncts_to_spaces(char line[])
{
        //line is a string
        //convert punctuations to spaces: use ispunct
}

void remove_spaces(char line[])
{
        //line is a string
        //remove the spaces and move the digits to the left
        //and put '\0' after the last digit
}

void format_number(char line[])
{
        //assuming the line size is big
        //insert dash or period after 3 and 6 
        size_t size = strlen(line);
        sprintf_s(line, MaxLine, "%c%c%c-%c%c%c-%c%c%c%c", line[0], line[1], line[2], 
                line[3], line[4],line[5], line[6], line[7], line[8], line[9]);
        //you can also do this instead
        //0123456789\0
        //012-345-6789\0
        //\0 is one char '\0'
        /*
        line[12] = '\0';
        line[11] = line[9];
        line[10] = line[8];
        line[9] = line[7];
        line[8] = line[6];
        line[7] = '-';
        line[6] = line[5];
        line[5] = line[4];
        line[4] = line[3];
        line[3] = '-';
        */
}

int main(void)
{
        enum { MaxLen = 255 };
        printf("Welcome to Quiz1\n");

        //read a string from the keyboard and process it
        while (true)
        {
                //code inside the loop
                char s1[MaxLine];
                puts("Enter an alphanumeric phone number (enter to quit) ");
                fgets(s1, MaxLen, stdin); //stdin from keyboard
                        //fgets reads text up to MaxLen-1, EOL including EOL
                s1[strlen(s1) - 1] = '\0'; //remove \n by replacing it with '\0'
                size_t len = strlen(s1);
                if (len == 0)
                        break;
                if (isValid(s1))
                {
                        toNumeric(s1);
                        printf("after toNumeric: ");
                        puts(s1); //fputs(s1, stdout); 
                        puncts_to_spaces(s1);
                        printf("after puncts_to_spaces: ");
                        puts(s1);
                        remove_spaces(s1);
                        printf("after remove_spaces: ");
                        puts(s1);
                        format_number(s1);
                        printf("after format_number: ");
                        puts(s1);
                }
                else
                        printf("invalid alphanumeric phone number\n");
        }
        return (0);
}

Answer 1

Please find the answer below.
Please do comments in case of any issue. Also, don't forget to rate the question. Thank You So Much.

code.c

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

enum { MaxLine = 255 };
bool isValid(char line[])
{
   int count = 0;
   while(line[count]!='\0'){
       if(!((line[count]>='a' && line[count]<='z')
               || (line[count]>='A' && line[count]<='Z')
               || (line[count]>='0' && line[count]<='9'))){
           return 0;
       }
       count++;
   }
   if(count==10){
       return 1;
   }
   return 0;
}

void toNumeric(char line[])
{
   //line is a string
   //use the switch statement we did in last lectures
   // (800) GOT - milk ; (800)GOT.milk, etc
   //convert letters to digits; leave rest as is.
   int count = 0;
   while(line[count]!='\0'){

       switch (toupper(line[count]))
       {
       case 'A':
       case 'B':
       case 'C':
           line[count]='2';
           break;
       case 'D':
       case 'E':
       case 'F':
           line[count]='3';
           break;
       case 'G':
       case 'H':
       case 'I':
           line[count]='4';
           break;
       case 'J':
       case 'K':
       case 'L':
           line[count]='5';
           break;
       case 'M':
       case 'N':
       case 'O':
           line[count]='6';
           break;
       case 'P':
       case 'Q':
       case 'R':
       case 'S':
       case 'T':
       case 'U':
       case 'V':
           line[count]='8';
           break;
       case 'W':
       case 'X':
       case 'Y':
       case 'Z':
           line[count]='9';
           break;
       }
      
       count++;
   }
}

void puncts_to_spaces(char line[])
{
   //line is a string
   //convert punctuations to spaces: use ispunct
   int count = 0;
   while(line[count]!='\0'){
       if(ispunct(line[count])){
           line[count] = ' ';
       }
       count++;
   }

}

void remove_spaces(char line[])
{
   //line is a string
   //remove the spaces and move the digits to the left
   //and put '\0' after the last digit
   int count = 0;
   while(line[count]!='\0'){
       if(line[count]==' '){

           int count2 = 0;
           while(line[count2]!='\0'){
               line[count2] = line[count2+1];
               count2++;
           }

       }
       count++;
   }
}

void format_number(char line[])
{
   //assuming the line size is big
   //insert dash or period after 3 and 6
   size_t size = strlen(line);
   sprintf(line, "%c%c%c-%c%c%c-%c%c%c%c", line[0], line[1], line[2],
           line[3], line[4],line[5], line[6], line[7], line[8], line[9]);
   //you can also do this instead
   //0123456789\0
   //012-345-6789\0
   //\0 is one char '\0'
   /*
line[12] = '\0';
line[11] = line[9];
line[10] = line[8];
line[9] = line[7];
line[8] = line[6];
line[7] = '-';
line[6] = line[5];
line[5] = line[4];
line[4] = line[3];
line[3] = '-';
   */
}

int main(void)
{
   enum { MaxLen = 255 };
   printf("Welcome to Quiz1\n");

   //read a string from the keyboard and process it
   while (true)
   {
       //code inside the loop
       char s1[MaxLine];
       puts("Enter an alphanumeric phone number (enter to quit) ");
       fgets(s1, MaxLen, stdin); //stdin from keyboard
       //fgets reads text up to MaxLen-1, EOL including EOL
       s1[strlen(s1) - 1] = '\0'; //remove \n by replacing it with '\0'
       size_t len = strlen(s1);
       if (len == 0)
           break;
       if (isValid(s1))
       {
           toNumeric(s1);
           printf("after toNumeric: ");
           puts(s1); //fputs(s1, stdout);
           puncts_to_spaces(s1);
           printf("after puncts_to_spaces: ");
           puts(s1);
           remove_spaces(s1);
           printf("after remove_spaces: ");
           puts(s1);
           format_number(s1);
           printf("after format_number: ");
           puts(s1);
       }
       else
           printf("invalid alphanumeric phone number\n");
   }
   return (0);
}