1.1
我使用g++，一般将C++程序命名为.cpp。
g++ -o main main.cpp
$ g++ -o main main.cpp
$ ls
main main.cpp1.2
将返回值改为-1后得到：
$ echo $?
255参考：
Exit Codes With Special Meanings
1.3
#include <iostream>
int main()
{
std::cout << "Hello,World" << std::endl;
return 0;
}1.4
#include <iostream>
int main()
{
std::cout << "Enter two numbers:" << std::endl;
int v1 = 0, v2 = 0;
std::cin >> v1 >> v2;
std::cout << "The product is " << v1 * v2 << std::endl;
return 0;
}1.5
#include <iostream>
int main()
{
std::cout << "Enter two numbers:" << std::endl;
int v1 = 0, v2 = 0;
std::cin >> v1 >> v2;
std::cout << "The product of ";
std::cout << v1;
std::cout << " and ";
std::cout << v2;
std::cout << " is ";
std::cout << v1 * v2;
std::cout << std::endl;
return 0;
}1.6
非法，修改为：
std::cout << "The sum of " << v1
<< " and " << v2
<< " is " << v1 + v2 << std::endl;1.7
$ g++ -o ex07 ex07.cpp
ex07.cpp: In function ‘int main()’:
ex07.cpp:5:3: error: expected primary-expression before ‘/’ token
*/
^
ex07.cpp:6:2: error: expected primary-expression before ‘return’
return 0;
^
ex07.cpp:6:2: error: expected ‘;’ before ‘return’1.8
第三行非法，第三行改为：
std::cout << /* "*/" */";1.9
#include <iostream>
int main()
{
int i = 50 ,sum = 0;
while(i <= 100)
{
sum += i;
++i;
}
std::cout << sum << std::endl;
return 0;
}1.10
#include <iostream>
int main()
{
int i = 10 ,sum = 0;
while(i >= 0)
{
sum += i;
--i;
}
std::cout << sum << std::endl;
return 0;
}1.11
#include <iostream>
int main()
{
int small = 0, big = 0;
std::cout << "please input two integers:";
std::cin >> small >> big;
if (small > big) {
int tmp = small;
small = big;
big = tmp;
}
while (small <= big) {
std::cout << small << " ";
++small;
}
std::cout << std::endl;
return 0;
}1.12
求从-100加到100的和，最终值为0。
测试代码如下：
#include <iostream>
int main()
{
int sum = 0;
for(int i = -100;i <= 100; i++ )
{
sum += i;
std::cout << i << std::endl;
}
std::cout << sum << std::endl;
return 0;
}1.13
Ex1.9:
#include <iostream>
int main()
{
int sum = 0;
for (int i = 50; i <= 100; ++i) sum += i;
std::cout << "the sum is: " << sum << std::endl;
return 0;
}Ex1.10:
#include <iostream>
int main()
{
for (int i = 10; i >= 0; --i)
std::cout << i << std::endl;
return 0;
}Ex1.11:
#include <iostream>
int main()
{
std::cout << "please input two integers:\n";
int small = 0, big = 0;
std::cin >> small >> big;
if (small > big)
{
int tmp = small;
small = big;
big = tmp;
}
for (int i = small; i != big; ++i)
std::cout << i << std::endl;
return 0;
}1.14
已知迭代次数时，使用for循环比较简洁；不知道迭代次数时使用while。
参考：
A similar question on Stack Overflow
1.15
请自行尝试。
1.16
#include <iostream>
int main()
{
int sum = 0, value = 0;
while(std::cin >> value)
{
sum += value;
}
std::cout << sum << std::endl;
return 0;
}数字输入完成后，Ctrl+d结束输入。
1.17
如果输入的所有值都是相等的，Ctrl+d后，才有输出统计的个数；如果没有重复输出，输入与前个不同的数即打印一行，Ctrl+d后，才输出最后一行统计的个数。
1.18
$ ./ex17
1 1 1 1 1
1 occurs 5 times
$ ./ex17
1 2 3 4 5
1 occurs 1 times
2 occurs 1 times
3 occurs 1 times
4 occurs 1 times
5 occurs 1 times1.19
见1.11。
1.20
#include <iostream>
#include "Sales_item.h"
int main()
{
Sales_item item;
std::cin >> item;
std::cout << item <<std::endl;
return 0;
}测试：
$ ./ex20
2-01 2 20
2-01 2 40 201.21
#include <iostream>
#include "Sales_item.h"
int main()
{
Sales_item item1,item2;
std::cin >> item1 >> item2;
std::cout << item1 + item2 <<std::endl;
return 0;
}$ ./ex21
1-01 2 100
1-01 3 100
1-01 5 500 1001.22
#include <iostream>
#include "Sales_item.h"
int main()
{
Sales_item item,sum_item;
std::cin >> sum_item;
while(std::cin >> item)
{
sum_item += item;
}
std::cout << sum_item << std::endl;
return 0;
}测试：
$ ./ex22
1-01 2 100
1-01 2 100
1-01 3 100
1-01 7 700 100需要初始化sum_item：
std::cin >> sum_item;
1.23
#include <iostream>
#include "Sales_item.h"
int main()
{
Sales_item currItem, valItem;
if (std::cin >> currItem) {
int cnt = 1;
while (std::cin >> valItem) {
if (valItem.isbn() == currItem.isbn())
++cnt;
else {
std::cout << currItem << " occurs " << cnt << " times "
<< std::endl;
currItem = valItem;
cnt = 1;
}
}
std::cout << currItem << " occurs " << cnt << " times " << std::endl;
}
return 0;
}1.24
测试：
$ ./ex23
1-01 2 100
1-01 3 100
1-01 1 100
1-02 1 150
1-01 2 200 100 occurs 3 times
1.25
#include <iostream>
#include "Sales_item.h"
int main()
{
Sales_item total; // variable to hold data for the next transaction
// read the first transaction and ensure that there are data to process
if (std::cin >> total) {
Sales_item trans; // variable to hold the running sum
// read and process the remaining transactions
while (std::cin >> trans) {
// if we're still processing the same book
if (total.isbn() == trans.isbn())
total += trans; // update the running total
else {
// print results for the previous book
std::cout << total << std::endl;
total = trans; // total now refers to the next book
}
}
std::cout << total << std::endl; // print the last transaction
} else {
// no input! warn the user
std::cerr << "No data?!" << std::endl;
return -1; // indicate failure
}
return 0;
}
测试：
$ ./ex25
1-01 2 100
1-01 3 100
1-01 1 100
1-02 1 150
1-01 6 600 100
1-02 1 150 150