練習答案

Exercise 1.1: Review the documentation for your compiler and determine what file naming convention it uses. Compile and run the main program from page 2. Exercise 1.2: Change the program to return -1. A return value of -1 is often treated as an indicator that the program failed. Recompile and rerun your program to see how your system treats a failure indicator from main.

#include<iostream>
int main(){
	return -1;
} 	

Exercise 1.3: Write a program to print Hello, World on the standard output.

int main(){
	std::cout<<"Hello,World"<<std::endl;
	return 0;
}

Exercise 1.4: Our program used the addition operator, +, to add two numbers. Write a program that uses the multiplication operator, *, to print the product instead.

#include<iostream>
int main(){
	std::cout<<"Enter two numbers"<<std::endl;
	int v1,v2;
	std::cin>>v1>>v2;
	std::cout<<"The product of "<<v1<<" and "
	        <<v2<<" is "<<(v1*v2)<<std::endl;
	return 0;
	
}

Exercise 1.5: We wrote the output in one large statement. Rewrite the program to use a separate statement to print each operand.

#include<iostream>
int main(){
	std::cout<<"Enter two numbers"<<std::endl;
	int v1,v2;
	std::cin>>v1>>v2;
	std::cout<<"The product of "<<v1<<" and "
	        <<v2<<" is "<<(v1*v2)<<std::endl;
	return 0;
	
}

Exercise 1.6: Explain whether the following program fragment is legal.

std::cout << "The sum of " << v1; 
                << " and " << v2; 
                << " is " << v1 + v2 << std::endl;

If the program is legal, what does it do? If the program is not legal, why not? How would you fix it?

不合法，可刪除第一第二行的分號或者在這兩行前面加上“std::cout”。 一種修改方式

    std::cout   << "The sum of " << v1 
                << " and " << v2 
                << " is " << v1 + v2 << std::endl;

Exercise 1.7: Compile a program that has incorrectly nested comments