getopt_long 命令参数解析函数欣赏

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getopt_long 命令参数解析函数欣赏

函数

原型

#include <getopt.h>

int getopt_long(int argc, char * const argv[], const char *optstring, const struct option *longopts, int *longindex);

输入

参数

int argc: 输入参数个数，包括可执行项

char * const argv[]：输入参数字符串指针数组，没个元素对应各个参数

const char *optstring：指向短参数常量的指针(参看例子)

h,单字符，只表示一个选项

v:r:b:,单字符后接冒号，表示必须跟参数，且紧跟字符后或用空格隔开, 该参数指针赋值给optarg

const struct option *longopts：指向结构体长参数常量的指针(参看例子)

struct option{

const char *name; //长参数名

int has_arg; //有三类参数，如下所示

int *flag; //NULL，返回长参数对对应短参数名

int val; // getopt_long返回值(实际与flag综合决定)

};

no_argument(或者是0)，表示该参数后面不跟参数值

required_argument(或者是1),表示该参数后面一定要跟个参数值

optional_argument(或者是2),表示该参数后面可以跟，也可以不跟参数值

int *longindex：通常为NULL

输出

参数

参数全部解析完成，返回-1

应用实例

下面是本人在DM6446项目中使用的代码，供大家学习.

/* ============================================================================ Name        : getopt_long.c Author      : sinonon Version     : v0.0 Copyright   : Your copyright notice Description : getopt_long in C, Ansi-style ============================================================================ */#include <stdio.h>#include <stdlib.h>#include <string.h>#include <getopt.h> #define __DEBUG/* Enables or disables debug output */#ifdef __DEBUG#define DBG(fmt, args...) fprintf(stderr, "XJTU_Encode: " fmt, ## args)#else#define DBG(fmt, args...)#endif#define ERR(fmt, args...) fprintf(stderr, "XJTU_EncodeError: " fmt, ## args) static void usage(void){    fprintf(stderr, "Usage: encode [options]\n\n"      "Options:\n"      "-v | --videofile   Video file to record to\n"      "-r | --resolution  Video resolution ('width'x'height') [720x576]\n"      "-b | --bitrate     Bit rate to encode video at [variable]\n"      "-t | --time        Number of seconds to run the demo [infinite]\n"      "-h | --help        Print this message\n\n"      "You must supply  a video file or\n"      "with appropriate extensions for the file formats.\n\n");} /****************************************************************************** * parseArgs ******************************************************************************/static void parseArgs(int argc, char *argv[]){const char shortOptions[] = "v:r:b:t:h";const struct option longOptions[]={{"videofile", required_argument, NULL, 'v'},{"resolution", required_argument, NULL, 'r'},{"videobitrate", required_argument, NULL, 'b'},{"time", required_argument, NULL, 't'},{"help", no_argument, NULL, 'h'},{0, 0, 0, 0}};    int     c;    char   *extension;    int     imageWidth;    int     imageHeight;    for (;;) {if(argc<2) {ERR("Input parameters error!\n"); break;}        c = getopt_long(argc, argv, shortOptions, longOptions,NULL);         if (c == -1) {break;}        switch (c) {            case 0:                break;                        case 'v':                extension = rindex(optarg, '.');                if (extension == NULL) {                    DBG("Video file without extension: %s\n", optarg);                    exit(EXIT_FAILURE);                }                if (strcmp(extension, ".264") == 0) {                    DBG("Init menu videoEncoder=H264_VIDEO_ENCODER\n ");                }                else if (strcmp(extension, ".mpeg4") == 0) {    DBG("Init menu videoEncoder=MPEG4_VIDEO_ENCODER\n ");                }                else {                    ERR("Unknown video file extension: %s\n",extension);                    exit(EXIT_FAILURE);                }                break;                        case 'r':                if (sscanf(optarg, "%dx%d", &imageWidth,&imageHeight) != 2) {                    ERR("Invalid resolution supplied (%s)\n",optarg);                    usage();                    exit(EXIT_FAILURE);                }DBG("Video resolution : %d x %d\n", imageWidth, imageHeight);                break;             case 'b':                DBG("videoBitRate: %d.\n",atoi(optarg));                break;            case 't':                DBG("time: %d.\n",atoi(optarg));                break;            case 'h':                usage();                exit(EXIT_SUCCESS);            default:                usage();                exit(EXIT_FAILURE);        }    }} int main(int argc, char *argv[]){   parseArgs(argc,argv);   return 0;}

代码测试

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