Question

please do in c++

Q4. Using recursion only (no loops allowed!), write a C++ function of the form int count7s(int) that when passed a non-negative integer, returns the number of occurrences of the digit 7 in the number. So, for example: 

count7s(717) → 2 

count75(7) →1 

count7s(123) → 0 

Q5. Write a C++ function of the form string mirrorEnds(string)that when given a string, looks for a mirror image (backwards) string at both the beginning and end of the given string. In other words, zero or more characters at the very beginning of the given string, and at the very end of the string in reverse order (possibly overlapping). For example, the string "abXYZba" has the mirror end "ab". 

mirrorEnds("abXYZba") → "ab" 

mirror Ends("abca") → "a" 

mirror Ends("navan") → "navan" 

Q6. Write a C++ function of the form int wordsCount(string[], int, int), where the first int is the size of the string array and the second int is the length (in characters) of the strings we wish to count. So, given an array of strings, return the count of the number of strings with the given length. 

wordsCount({"a", "bb", "b", "ccc"}, 4, 1) → 2 

wordsCount({"a", "bb", "b", "ccc"}, 4, 3) → 1 

wordsCount({"a", "bb", "b", "ccc"}, 4, 4) → 0

Answer 1

Q4)

CODE:

#include
using namespace std;
int count7s(int n){
   if(n==0)
       return 0;
   if(n%10==7)
       return 1+count7s(n/10);
   return count7s(n/10);  
}
int main(){
   cout<<count7s(717)<<endl;
   cout<<count7s(7)<<endl;
   cout<<count7s(123)<<endl;
}

OUTPUT:

Q5)

CODE:

#include
using namespace std;
void mirrorEnds(string s){
   int n=s.size();
   int end=n-1,i;
   for(i=0;i<n/2;i++){
       if(s[i]==s[end--])
           cout<<s[i];
       else
           return ;
   }
   if(i==n/2)
   {
       for(int j=i;j<n;j++)
       {
           cout<<s[j];
       }
   }
}
int main(){
   mirrorEnds("abXYZba");
   cout<<endl;
   mirrorEnds("abca");
   cout<<endl;
   mirrorEnds("navan");
}

OUTPUT:

Q6)

CODE:;

#include
using namespace std;
int wordsCount(string s[],int n,int len){
   int count=0;
   for(int i=0;i< n;i++){
       if(s[i].size()==len)
           count++;
   }
   return count;
}
int main(){
string s[]={"a","bb","b","ccc"};
   cout<<wordsCount(s,4,1) < < endl;
   cout<<wordsCount(s,4,3) < < endl;
   cout<<wordsCount(s,4,4) < < endl;
}

OUTPUT: