Finding sevens

Computer Science Level 2

How many times does the number '7' appear in String a? 

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String a = "1628261829271628239271982027282927827618227261434335242627282928276272728292918972625252728921011514252431524251524152524254253435241534223392028302029382002929102102929101192928101019298281910101010991929121900101010292991010101029920101092929128919010101929928912910101828272663272818182726256352562615624236252377777215252616252541256625421652392029281710000001010929298282781818288272718821827271288182712819889192919818991292191212272726167172762626216163515251.";


The answer is 32.

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Arpit MIshra by Arpit MIshra , 21, India

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15 solutions

John Taylor
Apr 12, 2015

Ctrl + F
Type 7
Count the number of times some number is highlighted

23 Helpful 0 Interesting 1 Brilliant 2 Confused

Moderator note:

Of course, you have to be careful that there are no other 7's hidden on the page. E.g. if the number of solvers is 77.

I just counted them

Oliver Blount - 6 years, 1 month ago

yuuupppzz same here

Trevor Arashiro - 6 years, 2 months ago

Doesn't apply to my phone :'(

Sherif Elbarbary - 6 years, 2 months ago

There goes my agreement.

Mark Diaz - 5 years, 8 months ago

I’m just starting and don’t know eneything

Sione Taione - 3 years, 1 month ago
Arpit MIshra
Apr 12, 2015

32 times. 

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String a = "...";
int count = 0;
int len=a.length();
for(i=0;i<len;i++)
{
if(s.charAt(i)=='7')
{
count++;
}
}
System.out.println("The number of times 7 appears in this String is "+a);

Output- The number of times 7 appears in this String is 32.

11 Helpful 0 Interesting 1 Brilliant 0 Confused

I did pretty much the same thing :)

Ariel Gershon - 6 years, 2 months ago
Sid 2108
Apr 13, 2015

You can just copy the whole number in MS Words and Press Ctrl+H to open the find and replace window and replace the number "7" with anything and it shows the number of replacement done in it...

7 Helpful 0 Interesting 0 Brilliant 0 Confused
Rama Rahardi
Apr 13, 2015 
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#include <iostream>
#include <cstring>
using namespace std;

int main() {
    int x = 0;
    char num[] = "1628261829271628239271982027282927827618227261434335242627282928276272728292918972625252728921011514252431524251524152524254253435241534223392028302029382002929102102929101192928101019298281910101010991929121900101010292991010101029920101092929128919010101929928912910101828272663272818182726256352562615624236252377777215252616252541256625421652392029281710000001010929298282781818288272718821827271288182712819889192919818991292191212272726167172762626216163515251";
    for (int i = 0; i < strlen(num); i++) {
        if (num[i] == '7') x++;
    }
    cout << x;
}

4 Helpful 0 Interesting 0 Brilliant 0 Confused
Arulx Z
Jun 17, 2015 
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String n = "...";
System.out.println(n.length() - n.replace("7", "").length());


1
 
'...'.count('7')

3 Helpful 0 Interesting 0 Brilliant 0 Confused

Common Python is way easier. Just see my answer.

Parth Agarwal - 5 years, 6 months ago

Log in to reply

I already posted the python solution in my answer. Check it again closely.

Arulx Z - 5 years, 6 months ago
Paulo Carlos
Apr 13, 2015

Simple.. .

3 Helpful 0 Interesting 0 Brilliant 0 Confused
Kishore S. Shenoy
Sep 16, 2015

int main() 

         {

                char c[500] =         

      `"1628261829271628239271982027282927827618227261434335242627282928276272728292918972625252728921011514252431524251524152524254253435241534223392028302029382002929102102929101192928101019298281910101010991929121900101010292991010101029920101092929128919010101929928912910101828272663272818182726256352562615624236252377777215252616252541256625421652392029281710000001010929298282781818288272718821827271288182712819889192919818991292191212272726167172762626216163515251.";`

        int no = 0;

        for (int i = 0; i < strlen(c); i++) {

        if (c[i]=='7') {

         no++;

       }

     }
    std::cout<<no;

    std::getchar();

    return 0;

   }
1 Helpful 0 Interesting 0 Brilliant 0 Confused

Moderator note:

Simple standard approach.

Mauricio H
Jul 21, 2015

Javascript: 

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strng  = <insert number here>;
count = 0;

for (var i in strng) {
    if (strng[i] == 7) {
        count += 1;
    }
}

document.write(count)

1 Helpful 0 Interesting 0 Brilliant 0 Confused
Karthik Kumar
Jul 13, 2015

a = "1628261829271628239271982027282927827618227261434335242627282928276272728292918972625252728921011514252431524251524152524254253435241534223392028302029382002929102102929101192928101019298281910101010991929121900101010292991010101029920101092929128919010101929928912910101828272663272818182726256352562615624236252377777215252616252541256625421652392029281710000001010929298282781818288272718821827271288182712819889192919818991292191212272726167172762626216163515251" b=[] count=0 for i in a: b.append(i) for t in b: if t=='7': count=count+1 print count

1 Helpful 0 Interesting 0 Brilliant 0 Confused
Gavince Daña
Apr 13, 2015

Ctrl + F Type 7 Count the number of times some number is highlighted

1 Helpful 0 Interesting 0 Brilliant 0 Confused 
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#include <iostream>
#include <string>
using namespace std;

int main()
{
    int ctr=0;
    string a = "1628261829271628239271982027282927827618227261434335242627282928276272728292918972625252728921011514252431524251524152524254253435241534223392028302029382002929102102929101192928101019298281910101010991929121900101010292991010101029920101092929128919010101929928912910101828272663272818182726256352562615624236252377777215252616252541256625421652392029281710000001010929298282781818288272718821827271288182712819889192919818991292191212272726167172762626216163515251.";

    for( int i=0 ; i<a.length() ; i++ )
    {
        if( a[i]=='7' )
            ctr++;
    }
    cout<<ctr<<endl;
    return 0;
}

1 Helpful 0 Interesting 0 Brilliant 0 Confused
Daniel Venable
Aug 22, 2018

Using Haskell you can do it in 2 lines!

count "" counter = counter

count string counter = if head string == head "7" then count (tail string) (counter + 1) else count (tail string) counter

0 Helpful 0 Interesting 0 Brilliant 0 Confused
Parth Agarwal
Nov 22, 2015

In Python:

z = "1628261829271628239271982027282927827618227261434335242627282928276272728292918972625252728921011514252431524251524152524254253435241534223392028302029382002929102102929101192928101019298281910101010991929121900101010292991010101029920101092929128919010101929928912910101828272663272818182726256352562615624236252377777215252616252541256625421652392029281710000001010929298282781818288272718821827271288182712819889192919818991292191212272726167172762626216163515251." x = z.count('7') print x

0 Helpful 0 Interesting 0 Brilliant 0 Confused
Vignesh Suresh
Oct 21, 2015

include<iostream.h>

void main() { char a[8000]="16282618292716282392719820272829278276182272614343352426272829282762727282929189726252527289210115142524315242515241525242542534352415342233920283020293820029291021029291011929281010192982819101010109919291219001010102929910101010299201010929291289190101019299289129101018282726632728181827262563525626156242362523777772152526162525412566254216523920292817100000010109292982827818182882727188218272712881827128198891929198189912921912122727261671727626 26216163515251";

int count=0;

for(int i=0;;i++) { if(a[i]!=0) {if(a[i]=='7')count++;} else break; }

cout<<count<<endl;

}

0 Helpful 0 Interesting 0 Brilliant 0 Confused
Agnaldo Cunha
Oct 8, 2015

Python is more elegant 

def how_many_7(string):
    count = 0
    for char in string:
        if char == '7':
            count += 1
    return count

print how_many_7('1628261829271628239271982027282927827618227261434335242627282928276272728292918972625252728921011514252431524251524152524254253435241534223392028302029382002929102102929101192928101019298281910101010991929121900101010292991010101029920101092929128919010101929928912910101828272663272818182726256352562615624236252377777215252616252541256625421652392029281710000001010929298282781818288272718821827271288182712819889192919818991292191212272726167172762626216163515251.')
0 Helpful 0 Interesting 0 Brilliant 0 Confused

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