我对我的 c 代码有疑问，
我的代码在做什么？
- 调用谷歌API“方向”
- 得到一个包含 json 结构的大字符串“s”
- 将我的字符串 s 写入文件
我的问题是什么？我想创建一个自动结构，因为我的结构总是不同的。例如，有时如果只有 200 或 1000 个坐标。
#include <stdio.h>
#include <curl/curl.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#define MAX 300
struct string {
char *ptr;
size_t len;
};
void init_string(struct string *s) {
s->len = 0;
s->ptr = malloc(s->len+1);
if (s->ptr == NULL) {
fprintf(stderr, "malloc() failed\n");
}
s->ptr[0] = '\0';
}
size_t writefunc(void *ptr, size_t size, size_t nmemb, struct string *s)
{
size_t new_len = s->len + size*nmemb;
s->ptr = realloc(s->ptr, new_len+1);
if (s->ptr == NULL) {
fprintf(stderr, "realloc() failed\n");
}
memcpy(s->ptr+s->len, ptr, size*nmemb);
s->ptr[new_len] = '\0';
s->len = new_len;
return size*nmemb;
}
void getRoad(double doubleLatitude, double doubleLongitude,char *villeDestination[MAX]){
printf("Function : getRoad\n");
printf("parameters latitude -%f-\n",doubleLatitude);
printf("parameters longitude -%f-\n",doubleLongitude);
printf("parameters villeDestination -%s-\n",villeDestination);
char URL_BASE[MAX],URL;
// CONVERT DOUBLE TO STRING
char stringLatitude[50];
char stringLongitude[50];
snprintf(stringLatitude, 50, "%f",doubleLatitude);
snprintf(stringLongitude, 50, "%f",doubleLongitude);
// WE ARE BUILDING URL URL
strcpy (URL_BASE,"https://maps.googleapis.com/maps/api/directions/json?origin=");
strcat(URL_BASE,stringLatitude);
strcat(URL_BASE,",");
strcat(URL_BASE,stringLongitude);
strcat(URL_BASE,"&destination=");
strcat(URL_BASE,villeDestination);
strcat(URL_BASE,"&avoid=highways&mode=bicycling&key=AIzaSyBpj0XoMAHi8naH5k-S8mAr0nexwCQvv2g");
// OUR URL, YOU CAN TEST IT IN FIREFOX !
printf("%s\n",URL_BASE);
CURL *curl;
CURLcode res;
curl_global_init(CURL_GLOBAL_DEFAULT);
curl = curl_easy_init();
if(curl) {
struct string s;
init_string(&s);
curl_easy_setopt(curl, CURLOPT_URL, URL_BASE);
#ifdef SKIP_PEER_VERIFICATION
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);
#endif
#ifdef SKIP_HOSTNAME_VERIFICATION
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L);
#endif
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writefunc);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, &s);
res = curl_easy_perform(curl);
printf("%s\n", s.ptr);//DEBUG
// OPEN A FILE AND WRITE DATA
FILE *fptr;
fptr = fopen("dataJson.json", "w");
if (fptr == NULL) {
printf("Error!");
exit(1);
}
fprintf(fptr, "%s", s.ptr);
fclose(fptr);
//printf("%s\n",curl_easy_perform(curl));//DEBUG
if(res != CURLE_OK)
fprintf(stderr, "curl_easy_perform() failed: %s\n",curl_easy_strerror(res));
curl_easy_cleanup(curl);
}
curl_global_cleanup();
}
/*
* Exemple type adepart avec des coordonnées
*
* origin 50.642782,2.833267
* destination paris
*
* https://maps.googleapis.com/maps/api/directions/json?origin=50.642782,2.833267&destination=paris&avoid=highways&mode=bicycling&key=AIzaSyBpj0XoMAHi8naH5k-S8mAr0nexwCQvv2g
*/
int main(void){
//getCoordinate();
// Coord depart - ville destination
getRoad(50.642782,2.833267,"nieppe");
return 0;
}
