How to pass argument got from ellipsis operator to other function? [duplicate]

问题

This question already has answers here:

Passing variable arguments to another function that accepts a variable argument list (8 answers)

Closed 4 years ago.

void myPrintf(const char* format, ...) {
    // some code
    va_list vl;
    printf(format, vl);
}

int main() {
    myPrintf("%d\n", 78);
}

In this code I have tried to pass the argument from ellipsis to printf. It compiles but prints garbage instead of 78. What is the right way of doing it?

回答1:

You need to do the following:

void myPrintf(const char *format, ...) {
    va_list vl;
    va_start(vl, format);
    vprintf(format, vl);
    va_end(vl);
}

Please note the use of vprintf instead of printf.

回答2:

Two problems:

1. The first is that you don't initialize vl, use va_start for that. Don't forget to use va_end afterwards.

2. The other problem is that printf doesn't take a va_list argument. Use vprintf for that.

回答3:

First Initialize vl

va_start(vl,1); //No. of arguments =1

Then take the int from it

printf(format, va_arg(vl,int));

来源：https://stackoverflow.com/questions/18715895/how-to-pass-argument-got-from-ellipsis-operator-to-other-function