C++ Programming Code Examples
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Copy elements from one vector to another vector
/* Copy elements from one vector to another vector
removing elements greater than 9 in the process */
#include <iostream>
using std::cout;
using std::endl;
#include <algorithm>
#include <vector>
#include <iterator>
bool greater9( int );
int main()
{
int a[ 10 ] = { 10, 2, 10, 4, 16, 6, 14, 8, 12, 10 };
std::ostream_iterator< int > output( cout, " " );
std::vector< int > v4( a, a + 10 ); // copy of a
std::vector< int > c2( 10, 0 ); // instantiate vector c2
cout << "Vector v4 before removing all elements"
<< "\ngreater than 9 and copying:\n ";
std::copy( v4.begin(), v4.end(), output );
std::remove_copy_if( v4.begin(), v4.end(), c2.begin(), greater9 );
cout << "\nVector c2 after removing all elements"
<< "\ngreater than 9 from v4:\n ";
std::copy( c2.begin(), c2.end(), output );
cout << endl;
return 0;
}
bool greater9( int x )
{
return x > 9;
}
/*
Vector v4 before removing all elements
greater than 9 and copying:
10 2 10 4 16 6 14 8 12 10
Vector c2 after removing all elements
greater than 9 from v4:
2 4 6 8 0 0 0 0 0 0
*/
copy() function is used to copy items from one iterator to another iterator with a specific range. We can define the start and end position of the source and it will copy all items in this rage to a different destination. To use copy() function, we need to include <bits/stdc+.h> or header file. It copies all the elements pointed by first and last. first element is included in the output but last is not. output is the start position of the final result iterator. It returns one iterator to the end of the destination range where elements have been copied. Function returns an iterator to the end of the destination range where elements have been copied.
Copy range removing values. Copies the elements in the range [first,last) to the range beginning at result, except those elements for which pred returns true. The resulting range is shorter than [first,last) by as many elements as matches, which are "removed". C++ Algorithm remove_copy_if() function is used to copy all elements in the range [first, last) to the range beginning at result, except those elements for which pred returns true without disturbing the order of the remaining elements. The function shall not modify its argument. This can either be a function pointer or a function object. The ranges shall not overlap.
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Put character. Inserts character c into the stream. Internally, the function accesses the output sequence by first constructing a sentry object. Then (if good), it inserts c into its associated stream buffer object as if calling its member function sputc, and finally destroys the sentry object before returning. Function returns the ostream object (*this).
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In computer programming, we use the if statement to run a block code only when a certain condition is met. An if statement can be followed by an optional else statement, which executes when the boolean expression is false. There are three forms of if...else statements in C++: • if statement, • if...else statement, • if...else if...else statement, The if statement evaluates the condition inside the parentheses ( ). If the condition evaluates to true, the code inside the body of if is executed. If the condition evaluates to false, the code inside the body of if is skipped.
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