# fill and fill_n STL Algorithms C++

## fill and fill_n STL Algorithms C++

The fill() and fill_n() algorithms fill a range with the value specified by val.

For fill() the range is specified by start and end.

Forfill_n(),ther range begins at start and runs for num elements.

#### fill Syntax:

```template < class ForwardIterator, class T >
void fill ( ForwardIterator first, ForwardIterator last, const T& value );

```

#### Source Code Example:

```
#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

typedef int type;

void print_vector(vector <type> vec0)
{
vector <type>::iterator it;
for ( it = vec0.begin( ) ; it != vec0.end( ) ; it++ )
cout << *it << " ";
cout<< endl;
}// print

int main( )
{
vector <type> vec0;

for ( int i = 0 ; i <= 10 ; i++ )
vec0.push_back(i*10 );

cout<< "vector : "<<endl;
print_vector(vec0);

fill (vec0.begin(),vec0.end()+4,0);
fill (vec0.begin()+5,vec0.end()-1,1);

cout<< "vector after the replace "<<endl;
print_vector(vec0);

}//edn of main
```

#### Program output:

```
vector :
0 10 20 30 40 50 60 70 80 90 100
vector after the replace
0 0 0 0 0 1 1 1 1 1 0

```

#### fill_n Syntax:

```
template < class OutputIterator, class Size, class T >
void fill_n ( OutputIterator first, Size n, const T& value );

```

#### Source Code Example:

```
#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

typedef int type;

void print_vector(vector <type> vec0)
{
vector <type>::iterator it;
for ( it = vec0.begin( ) ; it != vec0.end( ) ; it++ )
cout << *it << " ";
cout<< endl;
}// print

int main( )
{
vector <type> vec0;

for ( int i = 0 ; i <= 10 ; i++ )
vec0.push_back(i*10 );

cout<< "vector : "<<endl;
print_vector(vec0);

fill_n (vec0.begin(),3,-1);
fill_n (vec0.begin()+4,5,0);

cout<< "vector after the replace "<<endl;
print_vector(vec0);

}//edn of main

```

#### Program Output:

```
vector :
0 10 20 30 40 50 60 70 80 90 100
vector after the replace
-1 -1 -1 30 0 0 0 0 0 90 100

```
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