trying to count occurence of a number in an array

[cburns34]

hi im new to c++ so i apologize for any stupidly obvious mistakes. im trying count the amount of times a certain number appears in an array ive had a go from what ive seen in other posts but i dont think im even close heres the code so far:

#include <iostream>

using namespace std;

int main()
{

int mark, i;
int count = 0;
int numbers[14]={0,1,2,3,4,5,6,4,4,7,7,7,8,8};


cout<<"please enter the mark you need to count";
cin>> mark;

for (i = 0; i < count++;)
{
if (numbers[i] = mark)
{
++i;
}

cout <<count;
}


system ("pause");

return (0);
}

[Disch]

if (numbers[i] = mark)

Look closely. You are using assignment (=). You want comparison (==)

[cburns34]

thanks, but it still doesn't do anything it wont output the count :/

[deathmoon]

if (numbers[i] = mark)
{
++i;
}

1. Your for loop should loop from i = 0 to i = 14, not count, because your count is 0 so the for loop is not working.
It should be for(int i=0;i<14;++i)
2. should be '==' instead of '=' for comparison instead of assignment
3. use count++ instead of ++i.
your code means you check the 3rd element and jumped 2nd element if your 1st element is same as your input, not counting the occurence.

[cburns34]

that has helped and it does now output a number however it only says occurs once even if it occurs several times in the array.

[TwoOfDiamonds]

post your modified code :D

[cburns34]

heres the most recent version:

#include <iostream>

using namespace std;

int main()
{

int mark, i;
int count = 0;
int numbers[14]={0,1,2,3,4,5,6,4,4,7,7,7,8,8};


cout<<"please enter the mark you need to count\n";
cin>> mark;

for (i = 0; i <14; i++);
{
if (numbers[i] = mark)
{
count++;
}

cout <<"that mark occurs"<< count<< "times\n";
}


system ("pause");

return (0);
}

[TwoOfDiamonds]

if (numbers[i] = mark)
should be
if (numbers[i] == mark)

because the

=

operator means that you asign that value to numbers[i] and then if numbers[i] is equal with 0 the if statement will return false otherwise it will return true and the

==

operator means 'is equal to' .

[cburns34]

oops didnt notice that however now it outputs 0 for every thing.

[TwoOfDiamonds]

shouldn't cout <<"that mark occurs"<< count<< "times\n"; be outside the for loop ?

[cburns34]

yea, another silly mistake sorry however still the same problem as before :/

[TwoOfDiamonds]

for (i = 0; i <14; i++);
should be for (i = 0; i <14; i++)
remove the ';' because now it increases 'i' 14 times and then it checks the if statement 1 time

in the future instead of declaring 'i' in the beginning simply use
for (int i = 0; i <14; i++) so it's best performance and you avoid these bugs

[clanmjc]

#include <algorithm>

//where 'search' is some number you are searching for
count = (int) std::count (numbers , numbers + 14, search);

[TwoOfDiamonds]

@clanmjc :D that's a new approach for me :D but it looks just fine :D i might use it next time ^_^ works for other data types too , right ?

[cburns34]

there's a run-time error now which says the variable 'i' is being used without being initialized. and there are errors when i remove any semi colons.
heres the code ive got now:
#include <iostream>

using namespace std;

int main()
{

int mark,i ;
int count = 0;
int numbers[14]={0,1,2,3,4,5,6,4,4,7,7,7,8,8};


cout<<"please enter the mark you need to count\n";
cin>> mark;

for (int i = 0; i <14; i++);
{
if (numbers[i] == mark)
{
count++;
}


}
cout <<"that mark occurs"<< count<< "times\n";

system ("pause");

return (0);
}

[TwoOfDiamonds]

int mark, i ; should be int mark; so you won't declare i multiple times and you still didn't remove the semicolon from for (int i = 0; i <14; i++);

[clanmjc]

works for other data types too , right ?

Aye
http://www.cplusplus.com/reference/algorithm/count/

[TwoOfDiamonds]

Thanx a lot ^_^

[cburns34]

i get build errors when i remove any semi colons from the for loop and, i cant remove the 'i' from 'int mark, i ;' as it says "i is undefined"

[clanmjc]

He was talking about the last semi colon after the for loop.