付録

課題1の付録

• 引数のとりかた
• 整数の前を 0 で埋める
• 乱数の発生法

引数のとりかた

C 言語

#include <stdio.h>
#include <stdlib.h>
void usage(char * cmd){
  fprintf(stderr,"usage: %s ninzu\n",cmd);
}
int main(int ARGC, char* ARGV[]){
  int ninzu;
  if(ARGC!=2){
    usage(ARGV[0]);
    return 1;
  }
  ninzu=atoi(ARGV[1]);
  if(ninzu<=0){
    usage(ARGV[0]);
    return 1;
  }
  printf("%d\n",ninzu);
  return 0;
}

C++

#include <iostream>
#include <string>
int getNinzu(int ARGC, char *ARGV[]) throw (char const *){
  if(ARGC!=2){
    throw "Needs only one argument.";
  }
  int ninzu=std::atoi(ARGV[1]);
  if(ninzu<=0){
    throw "Value is too small.";
  }
  return ninzu;
}  
int main(int ARGC, char* ARGV[]){
  std::string cmdname=ARGV[0];
  int ninzu;
  try{
    ninzu=getNinzu(ARGC,ARGV);
  }catch(char const *str){
    std::cerr << str << std::endl
	      << "Usage: " << cmdname << " ninzu" << std::endl;
    return 1;
  }
  std::cout << ninzu << std::endl;
}

Java

class Test {
    private static int getNinzu(String str)
	throws NumberFormatException,
	       IllegalArgumentException {
	int value = Integer.valueOf(str);
	if(value<=0){
	    throw new IllegalArgumentException();
	}
	return value;
    }
    public static void main(String[] arg){
	String cmdname="Test";
	int ninzu;
	try{
	    ninzu=getNinzu(arg[0]);
	}catch(Exception e){
	    System.err.println(e.getClass().getName());
	    System.err.println("Usage: "+cmdname+" ninzu");
	    return ;
	}
        System.out.println(ninzu);
    }
}

整数の前を 0 で埋める

C言語

#include <stdio.h>
int main(void){
  printf("%05d\n",1);
  return 0;
}

C++

#include <iostream>
#include <iomanip>
int main(){
  std::cout << std::setw(5)
	    << std::setfill('0')
	    << 1
	    << std::endl;
}

Java

class Pad {
    public static void main(String[] args){
	System.out.println(String.format("%05d",1));
    }
}

乱数の発生法

C言語

#include <stdlib.h>
#include <time.h>
int myrand(void){
  static int firsttime=1;
  if(firsttime){
    firsttime=0;
    srand(time(NULL));
  }
  return (int)((double)rand()/(RAND_MAX+1.0)*(5+1));
}

C++

#include <cstdlib>
#include <ctime>
int randfive(){
  static bool firsttime=true;
  if(firsttime){
    firsttime=false;
    std::srand(std::time(NULL));
  }
  return static_cast<int>(static_cast<double>(std::rand())/(RAND_MAX+1.0)*(5+1));
}

Java

public class MyRand {
    public static int get(){
	return (int) (Math.random()*(5+1));
    }
}