我正在编写一个涉及boost :: program_options的C ++程序，在这里我遇到了一些问题。我的一些代码在这里给出。
int main(int argc, char* argv[]) {
options_description desc("useage: filterfq", options_description::m_default_line_length * 2, options_description::m_default_line_length);
options_description generic("Gerneric options", options_description::m_default_line_length * 2, options_description::m_default_line_length);
generic.add_options()
("help,h", "produce help message")
;
options_description param("Parameters", options_description::m_default_line_length * 2, options_description::m_default_line_length);
param.add_options()
("checkQualitySystem,c", bool_switch(), "only check quality system of the fastq file")
("baseNrate,N", value<float>() -> default_value(0.05), "maximum rate of \'N\' base allowed along a read")
("averageQuality,Q", value<float>() -> default_value(0), "minimum average quality allowed along a read")
("perBaseQuality,q", value<int>() -> default_value(5), "minimum quality per base allowed along a read")
("lowQualityRate,r", value<float>() -> default_value(0.5), "maximum low quality rate along a read")
("rawQualitySystem,s", value<int>(), "specify quality system of raw fastq\n0: Sanger\n1: Solexa\n2: Illumina 1.3+\n3: Illumina 1.5+\n4: Illumina 1.8+")
("preferSpecifiedRawQualitySystem,p", bool_switch(), "indicate that user prefers the given quality system to process")
;
options_description input("Input", options_description::m_default_line_length * 2, options_description::m_default_line_length);
input.add_options()
("rawFastq,f", value< vector<path> >() -> required() -> multitoken(), "raw fastq file(s) that need cleaned, required")
;
options_description output("Output", options_description::m_default_line_length * 2, options_description::m_default_line_length);
output.add_options()
("cleanQualitySystem,S", value<int>() -> default_value(4), "specify quality system of cleaned fastq, the same as rawQualitySystem")
("outDir,O", value<path>() -> default_value(current_path()), "specify output directory, not used if cleanFastq is specified")
("outBasename,o", value<string>(), "specify the basename for output file(s), required if outDir is specified")
("cleanFastq,F", value< vector<path> >() -> multitoken(), "cleaned fastq file name(s), not used if outDir or outBasename is specified")
("droppedFastq,D", value< vector<path> >() -> multitoken(), "fastq file(s) containing reads that are filtered out")
;
desc.add(generic).add(param).add(input).add(output);
variables_map vm;
store(command_line_parser(argc, argv).options(desc).run(), vm);
if (vm.count("help")) {
cout << desc << "\n";
return 0;
}
...
}
此处未给出使用命名空间部分的#include。当我输入命令以查看帮助消息时，它显示了以下内容
useage: filterfq:
Gerneric options:
-h [ --help ] produce help message
Parameters:
-c [ --checkQualitySystem ] only check quality system of the fastq file
-N [ --baseNrate ] arg (=0.0500000007) maximum rate of 'N' base allowed along a read
-Q [ --averageQuality ] arg (=0) minimum average quality allowed along a read
-q [ --perBaseQuality ] arg (=5) minimum quality per base allowed along a read
-r [ --lowQualityRate ] arg (=0.5) maximum low quality rate along a read
-s [ --rawQualitySystem ] arg specify quality system of raw fastq
0: Sanger
1: Solexa
2: Illumina 1.3+
3: Illumina 1.5+
4: Illumina 1.8+
-p [ --preferSpecifiedRawQualitySystem ] indicate that user prefers the given quality system to process
Input:
-f [ --rawFastq ] arg raw fastq file(s) that need cleaned, required
Output:
-S [ --cleanQualitySystem ] arg (=4) specify quality system of cleaned fastq, the same as rawQualitySystem
-O [ --outDir ] arg (="/home/tanbowen/filterfq") specify output directory, not used if cleanFastq is specified
-o [ --outBasename ] arg specify the basename for output file(s), required if outDir is specified
-F [ --cleanFastq ] arg cleaned fastq file name(s), not used if outDir or outBasename is specified
-D [ --droppedFastq ] arg fastq file(s) containing reads that are filtered out
帮助信息看起来有点难看，尤其是＆＃34; 0.0500000007＆＃34;，我想改进它。但我google了很长时间，我找不到解决方案。所以我在这里寻求帮助解决以下问题：
一个额外的问题：如何防止执行以下命令
filter -f <some file> -f <some file>
即，不允许多次指定相同的选项？
非常感谢!!
答案 0 :(得分：2)
是，请参阅下文（显示收集和显示格式化选项的一般形式）
查看options_description的构造函数。它允许您指定列宽。
以下是自定义选项值的（实际）示例。在我的情况下，我想收集一个以字节为单位的缓冲区大小，但也希望能够解析像4K或1M这样的东西。
struct bytesize_option
{
bytesize_option(std::size_t val = 0) : _size(val) {}
std::size_t value() const { return _size; }
void set(std::size_t val) { _size = val; }
private:
std::size_t _size;
};
std::ostream& operator<<(std::ostream& os, bytesize_option const& hs);
std::istream& operator>>(std::istream& is, bytesize_option& hs);
namespace {
static constexpr auto G = std::size_t(1024 * 1024 * 1024);
static constexpr auto M = std::size_t(1024 * 1024);
static constexpr auto K = std::size_t(1024);
}
std::ostream& operator<<(std::ostream& os, bytesize_option const& hs)
{
auto v = hs.value();
if (v % G == 0) { return os << (v / G) << 'G'; }
if (v % M == 0) { return os << (v / M) << 'M'; }
if (v % K == 0) { return os << (v / K) << 'K'; }
return os << v;
}
std::istream& operator>>(std::istream& is, bytesize_option& hs)
{
std::string s;
is >> s;
static const std::regex re(R"regex((\d+)([GMKgmk]){0,1})regex");
std::smatch match;
auto matched = std::regex_match(s, match, re);
if(!matched) {
throw po::validation_error(po::validation_error::invalid_option_value);
}
if (match[2].matched)
{
switch (match[2].str().at(0))
{
case 'G':
case 'g':
hs.set(std::stoul(match[1].str()) * G);
break;
case 'M':
case 'm':
hs.set(std::stoul(match[1].str()) * M);
break;
case 'K':
case 'k':
hs.set(std::stoul(match[1].str()) * K);
break;
}
}
else {
hs.set(std::stoul(match[1].str()));
}
return is;
}
你会像这样使用它：
return boost::shared_ptr<po::option_description> {
new po::option_description("server.max-header-size,x",
po::value(&_max_hdr_size)
->default_value(_max_hdr_size),
"The maximum size (in bytes) of a HTTP header "
"that the server will accept")
};
在这种情况下，定义了_max_hdr_size：
bytesize_option _max_hdr_size;