Setting number of looping - c

Question

I have problem. I need functions in tool.c file to loop only number of times that are required. Like it stops after looping thru whole input. My teacher said I should pass second argument, but class finished and I don't know how it should look.
main.c
#include <stdio.h>
#include <stdlib.h>
#include "tools.h"
int main(int argc, char *argv[]) {
int count[256] = { 0 };
int c;
while ( (c=getchar())!=EOF ){
count[c]++;
}
switch (argc > 1 && argv[1][1]) {
case 'm': case 'M':
mostOften(count);
break;
case 'l': case 'L':
leastOften(count);
break;
default:
mostOften(count);
break;
}
return 0;
}
tools.c
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include "tools.h"
void mostOften(int *s) {
int j, a = 0;
int max=0, cha;
for(j=32; j<126; j++){
if(s[j]>max) {
max=s[j];
cha=j;
}
a++;
}
printf("char %c: %d times\n", cha, max);
}
void leastOften(int *s) {
int j, a = 0;
int min=INT_MAX, cha;
for(j=32; j<126; j++){
if(s[j] && s[j]<=min) {
min=s[j];
cha=j;
}
a++;
}
printf("char %c: %d times\n", cha, min);
}
For example if I input
paragraph
I want it to loop only 9 times, basically I need to set some if statment to stop looping

Answer 1

From looking at how you have the problem setup, it looks like you are confusing iterating over the character that are part of the input, and the array that holds the frequency of the characters read.
For starters, to make your code readable, don't use magic numbers in your code, e.g. 32 and 126. Instead use the characters you are attempting to represent, e.g. (space) and ~ (tilde). For example, instead of using:
for(j=32; j<126; j++){
you could use:
for(j = ' '; j < '~'; j++){
That too has it's pitfalls. Why? You don't want to loop over characters, you actually want to loop over the elements in your count array that hold the frequency each character occurs in input. In other words, you need an array holding at minimum 95 integers which will hold the frequency each character occurs in your input. Since you know how may characters that will be, don't obscure it behind 32 to 126, just declare a constant for your array size (maybe called ARSZ) in tools.h, e.g.
#define ARSZ 95
Then after reading your input and filling the count array, it is just a matter of iterating over the count array once to get either the mostoften or leastoften number. Further, since you have a constant for the number of elements in count you do NOT need to pass the size of count to mostoften and leastoften -- you already know how many elements are present, 95. (see below for notes on iterating only over the characters present in input)
(if the array size is Not constant (and you are not passing an array with a sentinel like a nul-terminated string) or the number of elements you need to iterate over is not known at compile time, then you DO need to pass the size of the array to the functions.
(and another quick aside, C generally uses all lower-case for variable names, reserving all upper-case for constants and macros. You will not ordinarily see MixedCase or camelCase variable names in C, leave that for C++)
Next, while you should use getopt for processing command line arguments, you can use a quick hack of checking the second character of the arguments at issue, but you need to validate you have at least one argument to check and that the argument isn't an empty-string. Basically, you want to check:
if (argc > 1 && *argv[1]) /* check argc & not empty-string */
switch (argv[1][1]) {
case 'm':
mostoften (count);
break;
case 'M':
mostoften (count);
break;
case 'l':
leastoften (count);
break;
case 'L':
leastoften (count);
break;
default:
fprintf (stderr, "warning: unrecognized option, using 'mostoften'.\n");
mostoften (count);
}
else {
fprintf (stderr, "warning: no option given using 'mostoften'.\n");
mostoften (count);
}
note: you can't put two constant conditions together for any single case of your switch (some compilers provide non-standard extensions). Also note, you do not need a break in the default case, there is no fall-through possible.
Putting it altogether, you could write your tools.h similar to:
#include <stdio.h>
#include <limits.h>
#define ARSZ 95
int mostoften (int *a);
int leastoften (int *a);
Your tools.c as:
#include "tools.h"
int mostoften (int *a) {
int i, max = INT_MIN, cha = '0';
for (i = 0; i < ARSZ; i++)
if (a[i] > max) {
max = a[i];
cha = i + ' ';
}
printf ("char '%c' : %d times\n", cha, max);
return max;
}
int leastoften (int *a) {
int i, min = INT_MAX, cha = '0';
for (i = 0; i < ARSZ; i++)
if (a[i] < min) {
min = a[i];
cha = i + ' ';
}
printf ("char '%c' : %d times\n", cha, min);
return min;
}
You do know that if the max or min is the same for 2 different characters, you will select the first, and in the case of leastoften you will always select the first character with 0 frequency. To correct this problem, you will need to keep a second array (or 2D array, or struct) that tracks which characters were present in the input and only consider the frequency for those characters.
Finally, your main.c could be written something like:
#include "tools.h"
int main (int argc, char **argv) {
int c = 0, count[ARSZ] = {0};
while ((c = getchar ()) != EOF)
if (' ' <= c && c <= '~')
count[c - ' ']++;
if (argc > 1 && *argv[1]) /* check argc & not empty-string */
switch (argv[1][1]) {
case 'm':
mostoften (count);
break;
case 'M':
mostoften (count);
break;
case 'l':
leastoften (count);
break;
case 'L':
leastoften (count);
break;
default:
fprintf (stderr, "warning: unrecognized option, using "
"'mostoften'.\n");
mostoften (count);
}
else {
fprintf (stderr, "warning: no option given using 'mostoften'.\n");
mostoften (count);
}
return 0;
}
There are many different ways to accomplish this task, but given your initial code, this keeps with what appeared to be your intent. Look it over and let me know if you have any questions. If you want the easiest way to track the characters present in your input without using a struct, then simply declaring count as count[ARSZ][2] and using the additional element to indicate which characters were present would do. (you can pass the array to your functions as int a[][2] or int (*a)[2]) Good luck.