A program that reads a string & a character . Each occurrence of the given character (regardless of its case) is converted to opposite case.

#include(iostream.h)

#include(conio.h)

#include(string.h)

void main()

{

char str[30], ch, ch1;

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

cin.getline(str,30);

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

cin>>ch;

for(int i =0; str[i]!='\0'; ++i)

{

if(toupper(ch) = = toupper(str[i]))

  {

    if(str[i]>='A' && str[i]<='Z')

         str[i] = str[i] + 32;

     else

         str[i] = str[i] - 32;

}

}

cout<<"\n The Converted String is  "<< str;

getch();

}