Thread: Replace scanf() and fgets() with getchar()

I'm new to C programming and I am currently trying to alphabetize a list of words. As of now I have a working program (posted below), however I am trying to run it on a microprocessor that does not allow the use of scanf() or fgets(). I was wondering if there is a way around this by using getchar() and putchar() but still use the same logic to alphabetize the list.

Code:

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


void main() {
   int i, j, n;
   char s[10][20], t[20];


   scanf("%d",&n);                           //reads user input
   for (i = 0; i <= n; i++)
      fgets(s[i],20,stdin);


   for (i = 1; i < n; i++) {                 //sort through and compare words
      for (j = 1; j < n; j++) {
         if (strcmp(s[j - 1], s[j]) > 0) {
            strcpy(t, s[j - 1]);
            strcpy(s[j - 1], s[j]);
            strcpy(s[j], t);
         }
      }
   }


   printf("\nSorted List");                //print sorted words
   for (i = 0; i <= n; i++)
      printf("%s", s[i]);
}

Originally Posted by laserlight

Instead of fgets with stdin you can use getchar to keep reading characters until the array is filled, or a newline character, EOF or a read error is encountered.

Thank you for your response. But I have two questions.

1) With fgets, I am reading stdin into the array s[i]. However when I try to read getchar into the array s[i], I get an error "incompatible types when assigning char[20] and char." I'm assuming I get this error because of the double array, so how would I fix this?

2)I want the input to to be read in line by line. From your response you say I understand i can read getchar into an array until a new line character. So I'm trying to understand that once I hit new line will it stop reading from stdin? Or will it read line by line? I'm just a little confused by that

Originally Posted by Click_here

What Microcontroller/Compiler are you using?
Most c compilers have ways of using printf and scanf with USART/UART - Providing you set it up correctly.

I'm using the nexys 3 board.

Okay, I have attempted to read in the characters into an array, and this is what I have but it does not work. Right now it only put the number back to the terminal and then it stops putting characters. How could I fix this? Am I even on the right track???

Code:

#include <stdio.h>#include "platform.h"
#include "xparameters.h"
#include <string.h>




 int main()
{
    int i, j;
    char  string[10][20], t[20];
    int num;


    while(1)
    {
        char ch = getchar();
        if(ch == 0)
            continue;


        if(ch <= 0x39 && ch >= 0x30)  //to get number of words in list
        {
            putchar(ch);
            num = ch - 0x30;
        }
        
        return num;


        if (ch <= 0x61 && ch >= 0x7A) 
        {
            putchar(ch);
            for(i=0; i<=num; i++)
            {
                for(j=0; j<=20; j++)
                    ch = string[i][j];
            }
        if(ch == 0x0D)
            break;


        }
    }
}

I apologize if the code is "rough", like i said in my original post I am new to this. Thank you in advance for any recommendations.

As soon as code execution reaches line 28 (the "return" statement), the program ends. Nothing after that will be executed.

Code:

if (ch <= 0x61 && ch >= 0x7A)

Mistake here. How can 'ch' be both less than 0x61 and greater than 0x7A?

You should also use character literals for character comparisons, instead of hex values. i.e.

'0' instead of 0x30
'a' instead of 0x61
'z' instead of 0x7A
etc