Question

Topics: Arrays in C.

For this assignment, you will write a C program that uses its first command line parameter to compute and display a histogram of characters that occur in it.

Requirements:

Your program must compile and run correctly using the gcc compiler on ale.

You must write the corresponding function definitions for the following function prototypes:

// set all elements of the histogram to zero

void init_histogram(int histo[]);

// construct the histogram from string

void cons_histogram(char string[], int histo[]);

// display the histogram to the screen in a “nice” format

void display_histogram(int histo[]);

Your functions must work with the following program:

#include

#include

#define MAX_CHAR 255 // largest ASCII(Extended) value for characters

typedef unsigned char byte; // may be useful for casting(s)

void init_histogram(int histo[]);

void cons_histogram(char string[], int histo[]);

void display_histogram(int histo[]);

int main(int args, char *argv[])

{

int histo[256];

if (args == 2)

{

init_histogram(histo);

cons_histogram(argv[1], histo);

display_histogram(histo);

}

else

exit(1);

return 0;

}

void init_histogram(int histo[])

{

// your code here

}

void cons_histogram(char string[], int histo[])

{

// your code here

}

void display_histogram(int histo[])

{

// your code here

}

Outline:

Create / open a .c file using pico, in your UNIX account

Write the necessary C statementss to meet the game specification given above

Make sure to test your “program” when it is done

You really need to run your program a number of time to do this thoroughly

Notes(s):

Only those characters that occurred at least once are reported.

The minimal occurrence may very well not be unique.

The value of a char variable is an integer value and hence can be used as an index into the histogram – once casted as unsigned to be safe.

Sample Run(s):

% ./a.out hgfjkddjkrui3

3 appeared 1 time

d appeared 2 times

f appeared 1 time

g appeared 1 time

h appeared 1 time

i appeared 1 time

j appeared 2 times

k appeared 2 times

r appeared 1 time

u appeared 1 time

Answer 1

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

#define MAX_CHARS 255

typedef unsigned char byte;

void init_histogram(int histo[]);
void cons_histogram(char string[], int histo[]);
void display_histogram(int histo[]);

int main(int argc, char const *argv[])
{
   if(argc < 2){
       printf("Please pass commanf line argument\n");
       return 1;
   }
  
   char input[40];
   strcpy(input, argv[1]);
   int histo[MAX_CHARS];

   init_histogram(histo);

   cons_histogram(input, histo);

   display_histogram(histo);

   return 0;
}

void init_histogram(int histo[]){

   int i;

   for(i=0; i<MAX_CHARS; i++)
       histo[i] = 0;
}

void cons_histogram(char string[], int histo[]){
   int i;
   for(i=0; i<strlen(string); i++){

       int index = (int)string[i];
       histo[index]++; // increasign count
   }
}

void display_histogram(int histo[]){

   int i;
   //printf("Char\t\tCount\n");
   for(int i=0; i<MAX_CHARS; i++){
       if(histo[i] > 0){
       char c = (byte)i;
       printf("%c appeared %d time\n", c, histo[i]);
       //printf("%c\t\t%d\n", c, histo[i]);
   }
   }
}

-flrstweek firstweek firstweek gcc histogram.c firstweek ./a.out hgfjkddjkrui3 3 appeared 1 time d appeared 2 time f appeared 1 time g appeared 1 time h appeared 1 time i appeared 1 time j appeared 2 time k appeared 2 time r appeared 1 time u appeared 1 time firstweek