1、安装Oracle客户端库

需要安装Oracle客户端库，可以从Oracle官网下载并安装相应的客户端库。

2、配置环境变量

在系统环境变量中添加以下两个变量：

ORACLE_HOME：指向Oracle客户端库的安装目录

LD_LIBRARY_PATH：指向Oracle客户端库的安装目录和LD_LIBRARY_PATH

3、编写C语言代码

创建一个名为oracle_function.c的文件，编写以下代码：

#include <stdio.h>
#include <stdlib.h>
#include <oci.h>
#define ORA_EXIT exit(fprintf(stderr, "%s
", oraerr));
void check_error(OCIError *errhp, sword status) {
    if (status != OCI_SUCCESS && status != OCI_SUCCESS_WITH_INFO) {
        sb4 errcode = 0;
        text errbuf[512];
        OCIErrorGet((dvoid *)errhp, (ub4)1, (text *)NULL, &errcode, errbuf, (ub4)sizeof(errbuf), OCI_HTYPE_ERROR);
        ORA_EXIT;
    }
}
int main() {
    OCIEnv *envhp;
    OCIServer *srvhp;
    OCISvcCtx *svchp;
    OCIStmt *stmthp;
    OCIBind *bindhp;
    OCIDefine *defnp;
    OCIError *errhp;
    text *bufp;
    sb4 bufl;
    ub4 bufsz = 1024;
    ub4 val;
    sb4 pos;
    // 初始化OCI环境
    OCIEnvCreate(&envhp, OCI_DEFAULT, NULL, NULL, NULL, NULL, 0, NULL);
    OCIHandleAlloc(envhp, (dvoid **)&errhp, OCI_HTYPE_ERROR, 0, NULL);
    // 创建服务器上下文
    OCIHandleAlloc(envhp, (dvoid **)&srvhp, OCI_HTYPE_SERVER, 0, NULL);
    OCIServerAttach(srvhp, envhp, (text *)"your_database", strlen("your_database"), 0);
    // 创建服务上下文
    OCIHandleAlloc(envhp, (dvoid **)&svchp, OCI_HTYPE_SVC, 0, NULL);
    OCIAttrSet(svchp, OCI_HTYPE_SVC, srvhp, 0, OCI_ATTR_SERVER, envhp);
    // 准备SQL语句
    text *sql = (text *)"BEGIN your_package.your_function(:param1, :result); END;";
    OCIStmtPrepare(stmthp, errhp, sql, strlen((char *)sql), OCI_NTV_SYNTAX, OCI_DEFAULT);
    check_error(errhp, OCIStmtExecute(svchp, stmthp, errhp, 1, 0, NULL, NULL, OCI_DEFAULT));
    // 绑定输入参数
    OCIBindByName(stmthp, &bindhp, errhp, (text *)":param1", 1, &val, sizeof(val), SQLT_INT, 0, 0, 0, 0, 0, OCI_DEFAULT);
    check_error(errhp, OCIBindByName(stmthp, &bindhp, errhp, (text *)":param1", 1, &val, sizeof(val), SQLT_INT, 0, 0, 0, 0, 0, OCI_DEFAULT));
    // 绑定输出参数
    OCIBindByName(stmthp, &bindhp, errhp, (text *)":result", 1, &val, sizeof(val), SQLT_INT, 0, 0, 0, 0, 0, OCI_DEFAULT);
    check_error(errhp, OCIBindByName(stmthp, &bindhp, errhp, (text *)":result", 1, &val, sizeof(val), SQLT_INT, 0, 0, 0, 0, 0, OCI_DEFAULT));
    // 执行SQL语句
    check_error(errhp, OCIStmtExecute(svchp, stmthp, errhp, 1, 0, NULL, NULL, OCI_DEFAULT));
    // 获取输出参数的值
    check_error(errhp, OCIAttrGet(stmthp, OCI_HTYPE_STMT, &val, 0, OCI_ATTR_VAR_POINTER, envhp));
    printf("Result: %d
", val);
    // 释放资源
    OCIHandleFree(stmthp, OCI_HTYPE_STMT);
    OCIHandleFree(svchp, OCI_HTYPE_SVC);
    OCIHandleFree(srvhp, OCI_HTYPE_SERVER);
    OCIHandleFree(errhp, OCI_HTYPE_ERROR);
    OCIHandleFree(envhp, OCI_HTYPE_ENV);
    return 0;
}

4、编译代码

使用gcc编译器编译代码，并链接Oracle客户端库：

gcc o oracle_function oracle_function.c L/path/to/oracle/lib loci

5、运行程序

运行编译后的程序，将调用Oracle函数并输出结果：

./oracle_function