Example of accessing webservice in C language: webservice in C Language

Example of accessing webservice in C language: webservice in C Language

In a recent project, you need to access webservice to obtain some json data. The returned page content is only json data, not as complex as the actual page. So I don't want to introduce the tool library any more and simply implement it using socket.

The following code is not the actual project Source Code. It is a small example I extracted to share with you. The code itself is easy to understand, but it requires some socket programming and http protocol basics.

# Include <stdio. h> # include <sys/socket. h> # include <netinet/in. h> # include <errno. h> # include <time. h> int main () {int sockfd = 0; struct sockaddr_in ser_addr; char url [1024] = {0}; // Request Buffer char recvbuff [4096] = {0 }; // receives the buffer char * data = NULL; struct timeval time = {5, 0}; int ret = 0; // fills in the webservice host information memset (& ser_addr, 0, sizeof (ser_addr); ser_addr.sin_family = AF_INET; ser_addr.sin_port = hto Ns (80); ret = inet_ton (AF_INET, "127.0.0.1", & ser_addr.sin_addr.s_addr); if (ret <0) {perror ("ERROR"); return-1 ;} if (ret = 0) {puts ("ERROR: arguments error"); return-1 ;}// create socket sockfd = socket (AF_INET, SOCK_STREAM, 0 ); if (sockfd <0) {perror ("ERROR"); return-1 ;}// set the blocking time to 5 s ret = setsockopt (sockfd, SOL_SOCKET, SO_RCVTIMEO, (const char *) & time, sizeof (time); if (ret <0) {perror ("E RROR "); goto end;} // connect to webservice ret = connect (sockfd, (struct sockaddr *) & ser_addr, sizeof (struct sockaddr); if (ret! = 0) {perror ("ERROR"); goto end;} // fill other attributes in the request url header and add them by yourself. End snprintf (url, sizeof (url), "GET/test HTTP/1.0 \ r \ n") with a line break and press Enter "); // initiate an http request ret = send (sockfd, url, strlen (url), 0); if (ret <0) {perror ("ERROR"); goto end ;} puts ("send success"); // The page returns ret = recv (sockfd, recvbuff, sizeof (recvbuff), 0); if (ret <0) {perror ("ERROR"); goto end;} puts ("recv success"); // parse the returned page and point the data pointer to the data subject data = strstr (recvbuff, "\ r \ n"); data + = 4; // print the page if (data! = NULL) {puts (data);} end: close (sockfd); return 0 ;}