c++ 使用shell命令

#include <iostream>
#include <stdio.h>
#include <vector>
#include <unistd.h>
#include <sys/types.h>

//execute shell command
//执行一个shell命令，输出结果逐行存储在resvec中，并返回行数
int32_t myexec(const char *cmd, std::vector<std::string> &resvec) {
    resvec.clear();
    FILE *pp = popen(cmd, "r"); //建立管道
    if (!pp) {
        return -;
    }
    char tmp[]; //设置一个合适的长度，以存储每一行输出
    while (fgets(tmp, sizeof(tmp), pp) != NULL) {
        if (tmp[strlen(tmp) - ] == '\n') {
            tmp[strlen(tmp) - ] = '\0'; //去除换行符
        }
        resvec.push_back(tmp);
    }
    pclose(pp); //关闭管道
    return resvec.size();
}

int main(int argc, const char * argv[]) {

    std::vector<std::string> *vect = new std::vector<std::string>();
    pid_t pid = getpid();
    char *cmd = new char[];
    sprintf(cmd, "ps -p %d -o 'pid,pcpu,rss'",pid);
    std::cout<< cmd << std::endl;
    int32_t a = myexec(cmd, *vect);

    std::cout<< a << std::endl;

    int i = ;
    int count = vect->size();
    for (; i < count; i++) {
        std::cout<< (*vect)[i] <<std::endl;
    }

    return ;
}