C - number of characters from file
So, I want to create a program that takes into account the occurrence of each character in the file. For example:
4 instances of character 0x67 (g)
11 instances of 0x68 (h) character
etc.
I'm not sure how to display and count the instances.
Any thoughts?
#include <stdio.h>
const char FILE_NAME[] = "input.txt";
#include <stdlib.h>
int main() {
int count = 0; /* number of characters seen */
FILE *in_file; /* input file */
/* character or EOF flag from input */
int ch;
in_file = fopen(FILE_NAME, "r");
if (in_file == NULL) {
printf("Cannot open %s\n", FILE_NAME);
exit(8);
}
while (1) {
ch = fgetc(in_file);
if (ch == EOF)
break;
++count;
}
printf("Number of characters in %s is %d\n",
FILE_NAME, count);
fclose(in_file);
return (0);
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Here's what I came up with ...
#include<stdio.h>
#include<stdlib.h>
int main() {
/* a buffer to hold the count of characters 0,...,256; it is
* initialized to zero on every element */
int count[256] = { 0 };
/* loop counter */
int k;
/* file handle --- in this case I am parsing this source code */
FILE *fp = fopen("ccount.c", "r");
/* a holder for each character (stored as int) */
int c;
/* for as long as we can get characters... */
while((c=fgetc(fp))) {
/* break if end of file */
if(c == EOF) break;
/* otherwise add one to the count of that particular character */
count[c]+=1;
}
/* now print the results; only if the count is different from
* zero */
for(k=0; k<256; k++) {
if(count[k] > 0) {
printf("char %c: %d times\n", k, count[k]);
}
}
/* close the file */
fclose(fp);
/* that it */
return 0;
}
I will compile the code using the following command (GCC 4.8.1 on OS X 10.7.4)
gcc ccount.c -Wall -Wextra -pedantic -ansi
it compiles without warnings or errors; this is the output:
char
: 40 times
char : 190 times
char ": 6 times
char #: 2 times
char %: 2 times
char ': 1 times
char (: 11 times
char ): 11 times
char *: 23 times
char +: 3 times
char ,: 5 times
char -: 3 times
char .: 9 times
char /: 20 times
char 0: 5 times
char 1: 1 times
char 2: 3 times
char 5: 3 times
char 6: 3 times
char :: 1 times
char ;: 13 times
char <: 3 times
char =: 7 times
char >: 3 times
char E: 2 times
char F: 2 times
char I: 2 times
char L: 1 times
char O: 1 times
char [: 4 times
char \: 1 times
char ]: 4 times
char a: 29 times
char b: 4 times
char c: 36 times
char d: 15 times
char e: 49 times
char f: 25 times
char g: 4 times
char h: 22 times
char i: 36 times
char k: 9 times
char l: 19 times
char m: 5 times
char n: 35 times
char o: 38 times
char p: 9 times
char r: 34 times
char s: 22 times
char t: 49 times
char u: 16 times
char v: 1 times
char w: 4 times
char y: 2 times
char z: 3 times
char {: 5 times
char }: 5 times
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you need to use an array, check:
int charArray[256];
memset(charArray, 0, 256*sizeof(int)); // instead of memset, for 0 values you can you just {0}
while (1) {
ch = fgetc(in_file);
if (ch == EOF)
break;
charArray[ch]++;
}
for (int i=0; i<256; i++)
if (charArray[i] > 0)
printf("Number of character %c is %d\n", (char)i, charArray[i]);
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If you want to get the number of characters in the alphabet, it might look like this:
int counts[26];
memset(&counts[0], 0, sizeof(counts));
while ( (ch = fgetc(in_file)) != EOF) {
if (ch >= 'a' && ch <= 'z')
++count[ch - 'a'];
}
listing them can be simple:
for (char c = 'a'; c <= 'z', ++c)
printf("Count of '%c' is %d\n", c, count[c - 'a']);
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int strchro(char c, char *str) {
char *pch;
int found = 0;
pch=strchr(str,c);
while (pch!=NULL)
{
//printf("found at %d\n",pch-str+1);
found++;
pch=strchr(pch+1,c);
}
return found;
}
old function I wrote a while ago .. hope it helps;)
more details here: http://en.cppreference.com/w/c/string/byte/strchr
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You can use an array of 256 integers ( char
8-bit on many platforms ). Since the number of characters appearing in the file cannot be negative, the unsigned type makes sense.
unsigned charCount[256] = { 0 };
Each slot in the array represents the number of times a symbol with that value has appeared in this file.
while ((ch = fgetc(in_file)) != EOF)
{
// increment the count of character ch
charCount[ch]++;
}
When printing them, some characters are not printed or are spaces (this is especially applicable if you are reading a binary file), you can use the isprint
and functions isspace
found in the header ctype.h
.
for (int i = 0; i < 256; i++)
{
// only display characters with a count of at least 1
if (charCount[i] > 0)
{
if (!isprint(i) || isspace(i))
printf("%u instances of character %x\n", charCount[i], (unsigned) i);
else
printf("%u instances of character '%c'\n", charCount[i], i);
}
}
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