Helllppp!!! I/O and array problems

The first part I'm having trouble with is having the user type in the file name to read in to the array.

Second, I need to count the occurance of each element of the array and display the element next to it's number of occurances.

The text file looks like this: 1 2 3 2 6 7 4 5 3 7 4 5 2 4 7

Please help me!

My code looks like this: (Don't laugh)

Code:

---

#include <iostream>
#include <fstream>
#include <cstdlib>
#include<string>

using namespace std;

void sort(char a[], int number_used);

void swap_values(char& v1, char& v2);

int index_of_smallest(const char a[], int start_index, int number_used);

int main()
{
        char input_file[21];
        int number_used;
        ifstream in_stream;
        in_stream.open(input_file);
       
       
        cout<< "Please enter the name of the input file.\n";
        cin>> input_file;
        cin.read(input_file, 21);
        sort(input_file, number_used);
        while (!in_stream.eof())
        {
                for (int index = 0; index < number_used; index++)
                cout<< input_file[index] << " \n";
       
                in_stream.close();
        }
       
        return 0;
}

void sort(char a[], int number_used)
{
int index_of_next_smallest;
for (int index = 0; index < number_used - 1; index++)
{
index_of_next_smallest = index_of_smallest(a, index, number_used);
swap_values(a[index], a[index_of_next_smallest]);
}
}

void swap_values(char& v1, char& v2)
{
int num;
num = v1;
v1 = v2;
v2 = num;
}

int index_of_smallest(const char a[], int start_index, int number_used)
{
int min = a[start_index],
index_of_min = start_index;
for (int index = start_index + 1; index < number_used; index++)
if (a[index] < min)
{
min = a[index];
index_of_min = index;
}
return index_of_min;
}

---

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could you please put code tags over all the code so its easier to read and debug... thanks

first off,

Code:

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        cin>> input_file;
        cin.read(input_file, 21);

---

what you probably want there is:

Code:

---

cin.getline(input_file,21);

---

second, when you hit sort(), what exactly are you trying to sort? and finally, when you hit your while loop, you check for eof on a stream you never opened.

I didn't check anything past that, but fix that and see where it gets you. one more thing: I see you've included <string>, but don't use any strings anywhere... I'm not so sure you'd need <cstdlib> either...

since you're reading in integers, you can cheat:

1. create an int array and initialize to zero (make sure the highest index >= highest # in file)
2. get the filename from the user
3. open and check the file
4. read in a number, and increase the array in that index by 1
5. when you're done, close the file and go through the file printing out the index and number at that index

for example, if you read in a 7, increase integers[7] by 1. at the end, your array will look like (using your sample input):

Code:

---

integers[0]: 0
integers[1]: 1
integers[2]: 3
integers[3]: 2
integers[4]: 3
integers[5]: 2
integers[6]: 1
integers[7]: 3

---

just throw that into a loop that outputs the index and number in that index and you're all set.

I'm having other problems, now but you have helped me so much. :)