我的程序应该接受两个必需参数和三个可选参数,如下所示ATE <input file> <output file> [--threads] [--bass] [--treble]
(请注意,我还没有弄清楚如何接受<required>
参数,因此输入和输出文件在代码中定义为-i input_file和-o output_file)
我正在使用GNU库argp来解析命令行参数,我的文件基于third example。
我使用以下命令运行程序
$ ./ATE -i input_file.pcm -o output_file.pcm
Too few arguments!
Usage: ATE [OPTION...]
-p AMOUNT_OF_THREADS -b BASS_INTENSITY -t TREBLE_INTENSITY
input_file.pcm output_file.pcm
Try `ATE --help' or `ATE --usage' for more information.
threads: 2, bass: 4, treble: 4
opening file input.pcm
RUNNING!
done, saving to out.pcm
运行程序时,即使argp成功解析了输入和输出选项,我也会得到“参数太少”,正如您在输出中看到的那样。
打印出parse_opt中的参数数量,
cout << state->arg_num << endl;
在每次调用时给我0。该代码有点长,但是它是完全独立的,因此您可以编译它以供自己查看。
命令.cpp
使用命名空间std;
#include <stdlib.h>
#include <argp.h>
#include <iostream>
#include <string>
#include <errno.h>
struct arguments {
string input_file;
string output_file;
int threads;
int bass;
int treble;
};
static char doc[] = "Parallequaliser - a multithreaded equaliser application written in c++";
static char args_doc[] = "-p AMOUNT_OF_THREADS -b BASS_INTENSITY -t TREBLE_INTENSITY input_file.pcm output_file.pcm";
static struct argp_option options[] = {
{"input_file", 'i', "IN_FILE", 0, "an input file in pcm format"},
{"output_file", 'o', "OUT_FILE", 0, "an output file in pcm format"},
{"threads", 'p', "AMOUNT_OF_THREADS", OPTION_ARG_OPTIONAL, "amount of threads, min 2"},
{"bass", 'b', "BASS_INTENSITY", OPTION_ARG_OPTIONAL, "bass intensity, from 0 to 7"},
{"treble", 't', "TREBLE_INTENSITY", OPTION_ARG_OPTIONAL, "treble intensity, from 0 to 7"},
{0}
};
static error_t parse_opt (int key, char *arg, struct argp_state *state) {
struct arguments *arguments = (struct arguments *) state->input;
switch (key) {
case 'p':
if (arg == NULL) {
arguments->threads = 4;
} else {
arguments->threads = strtol(arg, NULL, 10);
}
break;
case 'b':
if (arg == NULL) {
arguments->bass = 4;
} else {
arguments->bass = strtol(arg, NULL, 10);
}
break;
case 't':
if (arg == NULL) {
arguments->treble = 4;
} else {
arguments->treble = strtol(arg, NULL, 10);
}
break;
case 'i':
if (arg == NULL) {
cout << "You forgot to specify the input file using the -i input_file.pcm option" << endl;
} else {
arguments->input_file = (string) arg;
}
break;
case 'o':
if (arg == NULL) {
cout << "You forgot to specify the out file using the -i output_file.pcm option" << endl;
} else {
arguments->output_file = (string) arg;
}
break;
case ARGP_KEY_ARG:
cout << "Key arg... " << key << endl;
if (state->arg_num > 5){
cout << "Too many arguments!" << endl;
argp_usage(state);
}
break;
case ARGP_KEY_END:
if (state->arg_num < 2){
cout << "Too few arguments!" << endl;
argp_usage(state);
}
break;
default:
return ARGP_ERR_UNKNOWN;
}
return 0;
}
static struct argp argp = { options, parse_opt, args_doc, doc };
int main (int argc, char **argv) {
struct arguments arguments;
arguments.threads = 2;
arguments.bass = 4;
arguments.treble = 4;
argp_parse(&argp, argc, argv, ARGP_NO_EXIT, 0, &arguments);
cout << "threads: " << arguments.threads << ", bass: " << arguments.bass << ", treble: " << arguments.treble << endl;
cout << "opening file " << arguments.input_file << endl;
cout << "RUNNING!" << endl;
cout << "done, saving to " << arguments.output_file << endl;
return 0;
}
最佳答案
对于argp解析器的上下文,这些选项不算作“参数”。
运行./ATE -i input_file.pcm -o output_file.pcm
时,“参数太少”,因为到达ARGP_KEY_END
,即参数的末尾,没有剩余参数。 arg_num
代表“独立”参数:已处理的ARGP_KEY_ARG
参数的数量。你什么都没有
为了确保您最初拥有两个必需的参数,请检查是否没有看到两个参数就不会到达ARGP_KEY_END
(就像您已经在做的那样:参数太少意味着您没有两个文件名)。 case ARGP_KEY_ARG
是您获取参数值的地方。