C++primer 4th 1.19
#include<iostream>
void print_range(int a, int b)
{
if (a > b)
{
print_range(b, a);
return;
}
int m = 1;
for (int val = a; val < b; ++val, ++m) {
std::cout << "the sequence of two integers are " << val << " " << "the number of m: " << m << std::endl;
if (m % 10 == 0) //while語句的時候有限制
std::cout << std::endl;
}
}
int main()
{
int a = 0, b = 0;
std::cout << "entering two integers:" << std::endl;
std::cin >> a >> b;
print_range(a, b);
return 0;
}
for語句中的可以定義多個變量:for(int val = a, m =1; val < b; ++val, ++m)
錯誤的使用while
while(條件) 或者 while(組合條件)
正確的做法是:
while(1){
if(條件1) break;
if(條件2) continue;
if(條件3)return;
}
// sum the numbers from 50 to 100 (use while)
#include <iostream>
auto sum(int lo, int hi)
{
int sum = 0;
while (lo <= hi) sum += lo++; // sum += lo ++,這個的優先級安排??
return sum;
}
int main()
{
std::cout << "Sum of 50 to 100 inclusive is: " << sum(50, 100) << std::endl;
return 0;
}
第一章彙總: