Python与C++程序的对比介绍

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。 我作到了，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。