C Expected Output Failure [closed] - c

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Here is my program.I am trying to find the frequency of each character of a string and display it. While answering please see to it that I don't want to try the ASCII concept and I want to know whats wrong with this concept.
#include <stdio.h>
#include <stdlib.h>
#include<string.h>
int main()
{
int l=0,j,k,m,count[10000];
char string[10000];
printf("Enter the string : \n");
scanf("%s",string);
l=strlen(string);
printf("%d",l);
for(j=0;j<l;j++)
{
for(k=j+1;k<l;k++)
{
if(string[j]==string[k])
{
count[j]++;
}
}
}
for(m=0;m<l;m++)
{
printf("%d",count[m]);
}
return 0;
}

Answer 1

So you wish to find the frequency of characters in your string.
About the mistakes in your code:
Consider the string lalal Here you would be counting the last l twice, once corresponding to first l and second time corresponding to third l. Hence your logic is faulty.
Similar is the case of count[]. You haven't initialized the array hence it holds garbage values.
So another approach to your problem could be declaring a 26-element array(English alphabet), iterate through the entire list and increment count corresponding to each element when that element is found.
int frequencyChar[26] = {0};//stores frequency of characters [a-z], initialized to zero
for( i=0; i<strlen(str); i++) //iterate through the entire string
{
frequencyChar[str[i] - 'a']++; //increment count corresponding to each element
}
for( i=0; i<26; i++)
{
printf("%d\n",frequencyChar[i]);
}
P.S.Above code assumes only lowercase characters in string. Minor changes would allow inclusion of uppercase letters!

Answer 2

Here are the problems:
You have written: I am trying to find the frequency of each character, but you code is attempting to calculate histogram of correlations between pairs of characters.
as an index for count you are using j, which iterates over constitutive characters in string. This means that your table count have lots of 0 and only some 1 and nothing else.
So currently this is NOT histogram of pairs of characters nor histogram of characters.
Character histogram can be created like this:
void makeStrHistogram(char *str, int histogram[256])
{
memset(histogram, 0, sizeof(histogram));
while (*str) histogram[*str++]++;
}
void printHistogram(int histogram[256])
{
for (int i=0; i<256; ++i) {
if (histogram[i]) {
printf("%c - %d\n", (char)i, histogram[i]);
}
}
}
To generate character correlation matrix:
void correlationMatrixForStr(char *str, int matrix[256][256])
{
memset(matrix, 0, sizeof(matrix));
int len = strlen(str);
for (int i=0; i<len; ++i) {
for (int j=i+1; j<len; ++j) {
matrix[i][j]++;
}
}
}