Question

I want to access the vector in the “manipulatevector” function below the same way as i access an array with vector[i] and not vector->at(i) in the code below. I have tried to pass the vector directly, and not a pointer as can be done with arrays. But this seem to corrupt the program. Any ideas how this can be achieved? Im new to using the std library, as i mostly have experience from C.

#include <vector>
#include <iostream>
#define vectorsize 5
struct st_test {
    int ii;
    float dd;
};

void manipulatevector(std::vector<struct st_test> *test) {
    test->resize(vectorsize);

    for(int i=0;i<vectorsize;i++) {
        test->at(i).dd = i*0.4f;
        test->at(i).ii = i;
    }
}

void manipulatearray(struct st_test test[vectorsize]) {
    for(int i=0;i<vectorsize;i++) {
        test[i].dd = i*0.4f;
        test[i].ii = i;
    }
}

void main() {
    std::vector<struct st_test> test1;
    manipulatevector(&test1);

    struct st_test test2[vectorsize];
    manipulatearray(test2);

    std::cout << "Vector" << std::endl;
    for(int i=0;i<vectorsize;i++) {
        std::cout << test1.at(i).dd << std::endl;
    }

    std::cout << "Array" << std::endl;
    for(int i=0;i<vectorsize;i++) {
        std::cout << test2[i].dd << std::endl;
    }
}

Answer 1

Have you tried passing the vector as a reference?

void manipulatevector(std::vector<struct st_test> &test) {
    test.resize(vectorsize);

    for(int i=0;i<vectorsize;i++) {
        test[i].dd = i*0.4f;
        test[i].ii = i;
    }
}

and

std::vector<struct st_test> test1;
manipulatevector(test1);