c语言socket传输图片

在C语言中使用Socket传输图片，可以按照以下步骤进行：

1. 打开图片文件并读取图片数据到内存中。

2. 创建Socket并连接到目标主机的Socket端口。

3. 将图片数据通过Socket发送到目标主机。

4. 目标主机接收到数据后，保存为图片文件。

以下是一个简单的示例代码：

发送端：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define SERVER_PORT 8888
#define MAXLINE 4096

int main(int argc, char **argv)
{
    int sockfd, n;
    char sendline[MAXLINE], recvline[MAXLINE];
    struct sockaddr_in servaddr;

    if (argc != 2) {
        printf("usage: ./client <ipaddress>\n");
        exit(0);
    }

    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        printf("create socket error\n");
        exit(0);
    }

    memset(&servaddr, 0, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(SERVER_PORT);
    if (inet_pton(AF_INET, argv[1], &servaddr.sin_addr) <= 0) {
        printf("inet_pton error for %s\n", argv[1]);
        exit(0);
    }

    if (connect(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr)) < 0) {
        printf("connect error\n");
        exit(0);
    }

    char *filename = "test.jpg";
    FILE *fp = fopen(filename, "rb");
    if (!fp) {
        printf("open file error\n");
        exit(0);
    }

    fseek(fp, 0, SEEK_END);
    int filesize = ftell(fp);
    fseek(fp, 0, SEEK_SET);

    char *imgdata = (char *)malloc(filesize);
    if (!imgdata) {
        printf("malloc error\n");
        exit(0);
    }

    fread(imgdata, 1, filesize, fp);
    fclose(fp);

    n = write(sockfd, (char *)&filesize, sizeof(filesize));
    n = write(sockfd, imgdata, filesize);

    free(imgdata);
    close(sockfd);

    return 0;
}

接收端：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define SERVER_PORT 8888
#define MAXLINE 4096

int main(int argc, char **argv)
{
    int listenfd, connfd, n;
    struct sockaddr_in servaddr, cliaddr;
    socklen_t clilen;
    char buf[MAXLINE];
    char *filename = "recv.jpg";
    FILE *fp;

    if ((listenfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
        printf("create socket error\n");
        exit(0);
    }

    memset(&servaddr, 0, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(SERVER_PORT);

    if (bind(listenfd, (struct sockaddr*)&servaddr, sizeof(servaddr)) == -1) {
        printf("bind error\n");
        exit(0);
    }

    if (listen(listenfd, 10) == -1) {
        printf("listen error\n");
        exit(0);
    }

    printf("waiting for client's request...\n");
    while (1) {
        clilen = sizeof(cliaddr);
        connfd = accept(listenfd, (struct sockaddr*)&cliaddr, &clilen);
        printf("accept a new client: %s:%d\n", inet_ntoa(cliaddr.sin_addr), cliaddr.sin_port);

        int filesize;
        n = read(connfd, &filesize, sizeof(filesize));
        printf("image size: %d\n", filesize);

        fp = fopen(filename, "wb");
        if (!fp) {
            printf("open file error\n");
            exit(0);
        }

        int len = 0;
        while (len < filesize) {
            n = read(connfd, buf, MAXLINE);
            fwrite(buf, 1, n, fp);
            len += n;
        }

        fclose(fp);
        close(connfd);

        printf("received image saved as %s\n", filename);
    }

    close(listenfd);

    return 0;
}

在这个示例中，我们使用TCP协议进行Socket通信，并且使用了JPEG格式的图片。注意在实际应用中，需要根据具体情况选择合适的协议和编码方式。