C++ is a general-purpose programming language. It has imperative, object-oriented and generic programming features, while also providing facilities for low-level memory manipulation. C++ is one of the most popular programming languages. It is based on C but is an object-oriented programming language. It is widely used in graphics libraries, games, network devices, etc.

//Program to find the length of a string without using library function

#include<iostream.h>

#include<conio.h>

#include<stdio.h>

 void main()

 {clrscr();

 char str[30];

 int len;

 cout<<"\n Enter a String :";

 gets(str);

 for(len=0;str(len)!='\0';++len);

 cout<<"\n The Length of The String="<<len;

 getch();

 }

//Program to calculate the number of vowels

#include<iostream.h>

#include<conio.h>

#include<stdio.h>

#include <ctype.h>

void CHARTYPE(char STRING[20]);

void main ()

{clrscr();

char string[20],ch;

cout<<"\n Enter a string:";

gets(string);

CHARTYPE(string);

getch();

}

void CHARTYPE(char string[20])

{char ch;

 int len,v=0,c=0,o=0,d=0;

 for(len=0;string[len]!='\0';++len)

 {if(isalpha (string[len]))

  {ch=toupper(string[len]);

   if(ch=='A'||ch=='E'||ch=='I'||ch=='0'||ch=='U')

   ++v;

   else

   ++c ;

  }

else if (isdigit (string[len]))

++d;

else

++o;

}

cout<<"\n There are "<<v<<"vowels,"<<c<<"constants,"<<d<<"digit and"<<o<<"other character in the given string :";

}

//program to enter a poem and to calculate number of vowel and consonants
#include<fstream.h>
#include<conio.h>
#include<process.h>
#include<ctype.h>
#include<string.h>
#include<stdio.h>
void main()
{ clrscr();
  char ch[100],charc,charw[10];
  int count1=0,count2=0;
  ofstream ofile;
  ofile.open("POEM.TXT",ios::out);
  if(!ofile)
  { cout<<"\n File can't be open";
exit(1);
  }
cout<<"\n Enter the poem:";
gets(ch);
ofile<<ch;

  ofile.close();
  ifstream ifile, ifile1;
  ifile.open("POEM.TXT",ios::in);
  if(!ifile)
  { cout<<"\n File can not read";
exit(1);
  }
  while(ifile>>charc)
  { charc=toupper(charc);
    if(charc=='A'||charc=='E'||charc=='I'||charc=='O'||charc=='U')
count1++;
  }

  cout<<"\n Number of vowel="<<count1;
  ifile.close();

  ifile1.open("POEM.TXT",ios::in);
  if(!ifile1)
  { cout<<"\n File can not read";
    exit(1);
  }
  while(ifile1)
{  ifile1>>charw;
if(strcmpi(charw,"the")==0)
count2++;
}
  cout<<"\n Number of 'the'="<<count2;
  ifile1.close();
  getch();
}

//program to maintain the record of candidates
#include<iostream.h>
#include<conio.h>
#include<string.h>
#include<stdio.h>
class CANDIDATE
{ int CRNo;
  char Name[10] ;
  float Score;
  char   Grade;
  void ComputeGrade();
 public:
  CANDIDATE()
  {CRNo =0;
   strcpy(Name,"Not Assigned");
   Score=0.0;
   Grade='-';
  }
  void inputdata();
  void displaydata();
};
  void CANDIDATE::inputdata()
  { cout<<"\n ENTER CRNo. :";
cin>>CRNo;
cout<<"\n ENTER YOUR NAME :";
gets(Name);
cout<<"\n ENTER YOUR SCORE:";
cin>>Score;
ComputeGrade();
   }
  void CANDIDATE::displaydata()
  {      cout<<"\n\n\t CRNo = "<<CRNo
<<"\n\t NAME ="<<Name
<<"\n\t SCORE ="<<Score
<<"\n\t Grade ="<<Grade;
  }
  void CANDIDATE::ComputeGrade()
  { if(Score>=90)
  Grade='A';
else if(Score>=75)
  Grade='B';
else if(Score>=60)
  Grade='C';
else if(Score>=45)
  Grade='D';
else if(Score>=33)
  Grade='E';
else
  Grade='F';
 }
void main()
{clrscr();
int i,pno;
CANDIDATE obj[2];
cout<<"\n ENTER THE DETAILS OF THE CANDIDATE";
for(i=0;i<2;i++)
{ cout<<"\n ENTER THE DETAILS OF THE CANDIDATE No "<<i+1;
  obj[i].inputdata();
}
for(i=0;i<2;i++)
{obj[i].displaydata();
 getch();
}

getch();
}

//program to count uppercase,lowercase,digits and other charcters
#include<iostream.h>
#include<conio.h>
#include<ctype.h>
#include<stdio.h>

void COUNT(char str[20]);

void main()
{clrscr();
 char string[20];
 cout<<"\n Enter a string: ";
 gets(string);
 COUNT(string);
 getch();
}

void COUNT(char str[20])
{int upper=0,lower=0,digit=0,other=0;
 for(int i=0; str[i]!='\0'; i++)
 {
  if(isupper(str[i]))
upper++;
  else if(islower(str[i]))
lower++;
  else if(isdigit(str[i]))
digit++;
  else
other++;
  }
  cout<<"\n Number of uppercase characters = "<<upper;
  cout<<"\n Number of lowercase characters = "<<lower;
  cout<<"\n Number of digits = "<<digit;
  cout<<"\n Number of other characters = "<<other;
 }