parse_args
csimpleshell.c (download)
1: void parse_args(char *buffer, char** args,
2: size_t args_size, size_t *nargs)
3: {
4: char *buf_args[args_size]; /* You need C99 */
5: char **cp;
6: char *wbuf;
7: size_t i, j;
8:
9: wbuf=buffer;
10: buf_args[0]=buffer;
11: args[0] =buffer;
12:
13: for(cp=buf_args; (*cp=strsep(&wbuf, " \n\t")) != NULL ;){
14: if ((*cp != '\0') && (++cp >= &buf_args[args_size]))
15: break;
16: }
17:
18: for (j=i=0; buf_args[i]!=NULL; i++){
19: if(strlen(buf_args[i])>0)
20: args[j++]=buf_args[i];
21: }
22:
23: *nargs=j;
24: args[j]=NULL;
25: }
To understand how it works, I suggest to take a look at the man page of strsep. As you can see this is a lot of code to perform a very simple task.
Compare with
argv = cmd.split()
The C++ version is a bit longer than the C version, but there is less "magic". In fact if you read the code it is very easy to understand how it works. Moreovere there is no hassle with memory allocation.
cppshell.cc (download)
1:
2: void
3: split_string(const std::string s,
4: const std::string sep,
5: std::vector<std::string> &components)
6: {
7: typedef std::pair<size_t, size_t> Range;
8: size_t pos, old_pos;
9: Range trange;
10: std::vector<Range> ranges;
11: trange.first = 0;
12: trange.second = s.find(sep, trange.first);
13: if (trange.second == string::npos){
14: trange.second = s.length();
15: }
16: ranges.push_back(trange);
17: while(trange.second < s.length()){
18: trange.first = trange.second + 1;
19: trange.second = s.find(sep, trange.first);
20: if (trange.second == string::npos){
21: trange.second = s.length();
22: }
23: ranges.push_back(trange);
24: }
25:
26: for (int i = 0; i < ranges.size() ; ++i){
27: components.push_back(s.substr(ranges[i].first,
28: ranges[i].second - ranges[i].first) );
29: }
30: }
In ObjectiveC there are methods (messages) like componentsSeparatedByString that make the task simpler.
