小程序：二分法//字符串转变成整数//删除代码里的注释

1、二分法：

//二分法:搜索已排序好的字符串组#include<iostream>using namespace std;int bisearch(char** arr,int b,int e,char* v){int minIndex=b,maxIndex=e,midIndex=0;while(minIndex < maxIndex){midIndex = minIndex + (maxIndex-minIndex)/2;int flag = strcmp(arr[midIndex] , v);if( flag < 0)minIndex = midIndex;else if( flag == 0)return midIndex;elsemaxIndex = midIndex;}return -1;}int main(){char* arr[] = {"ahello","bthe","cworld","dthanks","eyou","fvery","gmuch","kgdk"};int sz= sizeof(arr)/4;for(int i=0;i<sz;++i)cout<<bisearch(arr,0,sz,arr[i])<<endl;return 0;} 

 

2、字符串转变成整数

//实现字符串转化成整数//要求输入：“123445”，字符串里的字符是数字#include<iostream>using namespace std;int atoi(const char* str){int sz=0;int i=0;while(str[i] != '/0'){if(str[i]<48 || str[i]>57)return 0;++sz;//统计字符串的长度（不包括'/0')++i;}i=0;int integer=0;while(str[i] != '/0'){if(str[i]<48 || str[i]>57)return 0;else{int tempsize = sz-1;int bit =str[i]-48;//当前的位数while(tempsize--)bit *= 10;--sz;integer+=bit;++i;}}return integer;}int main(){char s[] = " 876543210";int Integer = atoi(s);cout<<"convert s to integer is: "<<Integer<<endl;return 0;} 

 

3、删除代码里的注释

//删除代码里的注释，注释以“//"大头，注释均位于单独的一行#include<iostream>#include<fstream>#include<vector>#include<string>using namespace std;ofstream& delete_cpp_code_annotation(ifstream& in,ofstream& out){string s;vector<string> svec;while(getline(in,s)) //把文件读入内存，存入vector<string>中{//cout<<s<<endl;svec.push_back(s);}//删除注释for(vector<string>::iterator it=svec.begin(); it<svec.end(); ++it){if(*it == "" ){out << "/n";continue;}if(*it != ""){int i=0;for(i=0;i<(*it).length();++i)if((*it)[i] != ' ')break;if((*it)[i] != '/') out << *it << "/n";} }return out;}int main(int argv1,char** argv2){ofstream outfile;string out_file_name = "NewCUP.txt";outfile.open(out_file_name.c_str());if(outfile)cerr<<"OK"<<endl;ifstream infile;string input_file_name = "CUP.txt";infile.open(input_file_name.c_str());if(!infile){cerr<<"error:unable to open file"<<endl;return -1;}delete_cpp_code_annotation(infile,outfile);outfile.close();infile.close();return 0;}