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Problem Description Uniform Resource Identifiers (or URIs) are strings like http://icpc.baylor.edu/icpc/, mailto:[email protected], ftp://127.0.0.1/pub/linux, or even just readme.txt that are used to identify a resource, usually on the Internet or a local computer. Certain characters are reserved within URIs, and if a reserved character is part of an identifier then it must be percent-encoded by replacing it with a percent sign followed by two hexadecimal digits representing the ASCII code of the character. A table of seven reserved characters and their encodings is shown below. Your job is to write a program that can percent-encode a string of characters. Character Encoding |
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Input The input consists of one or more strings, each 1–79 characters long and on a line by itself, followed by a line containing only "#" that signals the end of the input. The character "#" is used only as an end-of-input marker and will not appear anywhere else in the input. A string may contain spaces, but not at the beginning or end of the string, and there will never be two or more consecutive spaces. |
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Output For each input string, replace every occurrence of a reserved character in the table above by its percent-encoding, exactly as shown, and output the resulting string on a line by itself. Note that the percent-encoding for an asterisk is %2a (with a lowercase "a") rather than %2A (with an uppercase "A"). |
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Sample Input Happy Joy Joy! http://icpc.baylor.edu/icpc/ plain_vanilla (**) ? the 7% solution # |
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Sample Output Happy%20Joy%20Joy%21 http://icpc.baylor.edu/icpc/ plain_vanilla %28%2a%2a%29 ? the%207%25%20solution |
本题核心：C++的字符串输入、输出等操作问题
1.基本输入
char buf[50];
cin>>buf;
这种方法输入会忽略最初的空白字符（换行符、空格符、制表符），而且会在下一个空格字符或换行符结束。
2.getline() 不定长输入字符串
string buf; //在C++中则把字符串封装成了一种数据类型string，可以直接声明变量并进行赋值等字符串操作。
getline(cin,buf);
对于getline()，读入整行数据，使用回车键的换行符来确定输入结尾。
3.getline()定长输入字符串
char buf[255];
cin.getline(buf,255);
读入整行数据，使用回车键的换行符来确定输入结尾，不保存换行符，在存储字符串时，用空值字符来替换换行符。
比如：
cin.getline(buf,5)
输入：abcde
输出：abcd （由于buf长度为5，输出时，最后一个为空值字符结尾，所以无法打印e）
4.string类和c字符串之间的转换。
可以将C字符串存储在string类型的变量中。
char a[]="Hello";
string b;
b=a;
但是string对象不能自动的转换为C字符串，需要进行显式的类型转换，需要用到string类的成员函数c_str()
例如：strcpy(a,b,c_str());
5.字符串到数字的转换
atoi函数获取一个C字符串参数，返回对应的int值。如果参数不与一个int值对应，atoi就会返回0.atoi函数在文件为cstdlib的库中。如果数字太大，不能转换为int类型的值，可以使用atoi将字符串转换为long类型的值
atoi("1234");//返回整数1234
atoi("#123");//返回0
6.string类的大小
string buf;
auto len ＝ buf.size();
len的数据类型不确定是int型还是无符号类型，所以使用auto。（还待深究....）
本题代码：
#include <iostream>
#include <string>
using namespace std;
int main() {
string str;
while (getline(cin,str) && str !="#")
{
auto len=str.size();
for (int i=0; i<len; i++) {
switch (str[i]) {
case ‘ ‘:cout<<"%20";break;
case ‘!‘:cout<<"%21";break;
case ‘$‘:cout<<"%24";break;
case ‘%‘:cout<<"%25";break;
case ‘(‘:cout<<"%28";break;
case ‘)‘:cout<<"%29";break;
case ‘*‘:cout<<"%2a";break;
default:
cout<<str[i];break;
}
}
cout<<"\n";
}
return 0;
}