While learning the basic usage of strings in C, I discovered that sstream's istringstream[1] can input strings in a console-like manner. In fact, this behavior is equivalent to using spaces to enter a string. segmentation.
So I considered that this feature can be used to implement the string splitting function split
string src("Avatar 123 5.2 Titanic K"); istringstream istrStream(src); //建立src到istrStream的联系 string s1, s2; int n; double d; char c; istrStream >> s1 >> n >> d >> s2 >> c; //以空格为分界的各数值则输入到了对应变量上
Implementation details
The purpose is to easily obtain the processed string array by calling a function just like in js, and then adjust the parameters according to the actual situation of c.
1. Input and output:
string* split(int& length, string str, const char token = ' ')
Return: the first address of the processed string array
Pass in: string str, delimiter token (default The parameter is a space), and the reference parameter length, indicating the length of the dynamically allocated array after processing
2. Data transparent processing:
Since istringstream will treat spaces like cin, is the boundary between data, so when the delimiter is not a space, the incoming delimiter needs to be replaced with a space, and the original space must be processed transparently in advance
Character replacement uses replace() in the library algorithm [2]
const char SPACE = 0; if(token!=' ') { // 先把原有的空格替换为ASCII中的不可见字符 replace(str.begin(), str.end(), ' ', SPACE); // 再把分隔符换位空格,交给字符串流处理 replace(str.begin(), str.end(), token, ' '); }
假设输入字符串为:"a b,c,d,e,f g" 分隔符为非空格:',' 则被替换为:"aSPACEb c d e fSPACEg"
3. Data segmentation:
//实例化一个字符串输入流,输入参数即待处理字符串 istringstream i_stream(str); //将length置零 length = 0; queue<string> q; //用一个string实例s接收输入流传入的数据,入队并计数 string s; while (i_stream>>s) { q.push(s); length++; }
4. Array generation:
//根据计数结果动态开辟一个字符串数组空间 string* results = new string[length]; //将队列中的数据转入数组中 for (int i = 0; i < length; i++) { results[i] = q.front(); //将替换掉的空格进行还原 if(token!=' ') replace(results[i].begin(), results[i].end(), SPACE, ' '); q.pop(); }
Complete code
#include <iostream> #include <string> #include <queue> #include <sstream> #include <algorithm> using namespace std; string* split(int& length, string str,const char token = ' ') { const char SPACE = 0; if(token!=' ') { replace(str.begin(), str.end(), ' ', SPACE); replace(str.begin(), str.end(), token, ' '); } istringstream i_stream(str); queue<string> q; length = 0; string s; while (i_stream>>s) { q.push(s); length++; } string* results = new string[length]; for (int i = 0; i < length; i++) { results[i] = q.front(); q.pop(); if(token!=' ') replace(results[i].begin(), results[i].end(), SPACE, ' '); } return results; } //测试: int main() { int length; string* results = split(length, "a b,c,d,e,f g", ','); for (int i = 0; i < length; i++) cout<<results[i]<<endl; return 0; }
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