Python与C++ 程序的简单实例对比

一位网友正在学校做课程设计题目,要求在一个文件中找到给定单词出现的位置并统计出现次数。这是一个比较简单的文本处理问题， 于是， 我给他用 python 写了一个，并打赌在5分钟内用不到30行程序解决问题。

下面是程序：

if __name__=='__main__':

file_name = raw_input('Input the file you want to find in:')

try:

in_file = open(file_name,'r')

lines = in_file.readlines()

        tag_tok = ''

while tag_tok.upper() != 'Q':

tag_tok = raw_input('Input the word you want to find(Q for quit):')

if tag_tok.upper() != 'Q':

count = 0

line_no = 0

for line in lines:

line_no = line_no + 1

inline_cnt = line.count(tag_tok)

count = count + inline_cnt

if inline_cnt > 0:

print 'Find %s %d time(s) in line :%d'%(tag_tok,inline_cnt,line_no)

print line

print '---------------------------------'

print 'Total fount %s %d time(s)'%(tag_tok, count)

except:

print "Can't open file %s"%(file_name)

但是，这个网友还不满足非要一个 C++的程序，理由是他们老师不会python ， 正好我也想试试用C++解决和python做下对比：

#include <fstream>

#include <iostream>

#include <string>

#include <vector>

#include <algorithm>

using namespace std;

int BruteFind(const char *x, int m, const char *y, int n ,vector<int>& colpos) {

int i, j, cnt=0;

/* Searching */

for (j = 0; j <= n - m; ++j) {

for (i = 0; i < m && x == y[i + j]; ++i);

if (i >= m){

colpos[cnt++] = j;

if(cnt == colpos.size())

colpos.resize(cnt * 2);

}

}

return cnt;

}

int count_string(string source, string tag, vector<int>& colpos){

int find_cnt = 0;

find_cnt = BruteFind(tag.c_str(), tag.size(), source.c_str(),source.size(),colpos);

  return find_cnt;

}

int main(){

string file_name, line;

vector<string> lines;

lines.resize(10);



cout << "Input the file name:";

cin  >> file_name;

ifstream in_file;

try{

in_file.open(file_name.c_str());

if(!in_file)

throw(file_name);

}

catch(string file_name){

cout << "Fatal error: File not found."<<endl;

exit(1);

}

int line_count = 0;

do{

getline(in_file, lines[line_count]);

line_count ++;



if(line_count == lines.size()){

lines.resize(line_count * 2);

}

}while(in_file.eof()==0);

string tag_tok;

vector<int> colpos;

colpos.resize(10);

do{

cout << "Input the word you want to find(Q for quit):";

cin >> tag_tok;

if(tag_tok == "Q"){

break;

}



int count = 0, line_no = 0 , inline_count;

for(line_no = 0 ;line_no < line_count ; line_no++){

inline_count = count_string(lines[line_no], tag_tok, colpos);

count += inline_count;

if(inline_count > 0){

cout << "Find " << tag_tok << " " << inline_count << " time(s) in line " << line_no ;

cout << " , column pos is ( ";



for(int i = 0 ;i< inline_count ;i++){

cout << colpos << ' ';

}

cout << " )" << endl;

cout << lines[line_no] << endl;

}

}

cout << "--------------------------------" <<endl;

cout << "Total fount " << tag_tok << " " << count << " time(s)" << endl;

}while(tag_tok != "Q");

in_file.close();

return 0;

}

这个程序用了30分钟。

从程序长度和编程时间上，粗略对比下：

Python  5 分钟 22行

C++       30 分钟 60多行

从这个简单的例子中可以大体看到 脚本语言与C++语言中在开发时的差异了。

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