laboratorio funciones, arreglos

#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <ctime>
using namespace std;
int main(){
srand(time(0));
for( int i=1;i<=20;i++){
  cout<<setw(10)<<(1+rand()%6);
  if (i%5==0) { cout<<endl; }
}
unsigned seed;
cout<<"Ingrese semilla: ";cin>>seed;
srand(seed);
for( int i=1;i<=20;i++){
  cout<<setw(10)<<(1+rand()%6);
  if (i%5==0)
    cout<<endl;
}
// use #include <ctime>
// para ejecutar srand(time(0))
system("PAUSE");
}



#include <iostream>
#include <cstdlib>
using namespace std;
float f_pol(float,int);//prototipo
int main(){
  float x; int n;
  cout<<"x=";cin>>x;
  cout<<"n=";cin>>n;
  cout<<"p(x)="<<f_pol(x,n)<<endl;
  system("PAUSE");
}
float f_pol(float x,int n){
    float z=1,t=1;
    for (int i=1;i<=n;t*=x,z+=t,i++);
    return z;
}


#include <iostream>
#include <cstdlib>
#include <cmath>
using namespace std;
float hipo1(float,float);
void hipo2(float,float, float&);
int main(){
  float a,b,c;
  cout<<"(a,b)=";cin>>a>>b;
  cout<<"c="<<hipo1(a,b)<<endl;
  hipo2(a,b,c);
  cout<<"c="<<c<<endl;
  system("PAUSE");
}
float hipo1(float a,float b){
  return sqrt(a*a+b*b);}
void hipo2(float a,float b,float& c){
  c = sqrt(a*a+b*b);}


#include <iostream>
#include <cstdlib>
using namespace std;
float eval(float[],float,int);
int main(){
  float x;int n;
  float A[]={1, 3,-4,5};
  n=4;
  cout<<"x=";cin>>x;
  cout<<"p(x)="<<eval(A,x,n)<<endl;
  system("PAUSE");
}
float eval(float A[],float x,int n){
  float z=0,t=1;
  for(int i=0;i<n;z+=t*A[i++],t*=x);
  return z;
}




#include <iostream>
#include <cstdlib>
using namespace std;
int dias_del_mes(int );
int main(){
  int m;
  do {
  cout<<"mes(1-12)=";cin>>m;
  }while( m<1 || m>12 );
  cout<<"tiene "<<
       dias_del_mes(m)<<endl;
  system("PAUSE");
}
int dias_del_mes(int m){
  switch(m){
    case 1:case 3:case 5:
    case 7:case 8:case 10:case 12: return 31;
    case 4:case 6:case 9:case 11: return 30;
    case 2: return 28;
  }
}