Mac Terminal编译错误

Question

Note: I do have xcode installed as well as its command line tools.

gcd.cpp:6:20: fatal error: iostream : No such file or directory

Is the error I get in terminal when running:

g++ gcd.cpp -o gcd -g -Wall -Werror -pedantic-errors -fmessage-length=0

I have no idea how to fix this issue. Any one know how to fix it?

#include <stdio.h>
#include <iostream>
#include <sstream>

using namespace std;

int gcdRecur(int a, int b) {
    if(b == 0)
        return a;
    else    
        return gcdRecur(b, a % b);
} 

int gcdIter(int a, int b) {
    int z;
        while(b != 0) {
            z = b;
            b = a%b;
            a = z;
        }
        return a;
}

int main(int argc, char *argv[]) {
    if(argc != 3){
        printf("Usage: %s <integer m> <integer n>", argv[0]);
        return -1;
    }
    string m_str = (string) argv[1];
    string n_str = (string) argv[2];
    istringstream iss;
    int m = 0, n = 0;
    iss.str(m_str);
    // Check if the first argument is an integer
    // by giving the istringstream 0
    if(!(iss >> m)){
        cerr << "Error: The first argument is not a valid integer." << endl;
        return -1;
    }
    iss.clear();
    iss.str(n_str);
    if(!(iss >> n)){
        cerr << "Error: The second argument is not a valid integer." << endl;
        return -1;
    }
    int iter = gcdIter(m, n);
    int recur = gcdRecur(m, n);
    printf("Iterative: gcd(%d, %d) = %d\nRecursive: gcd(%d, %d) = %d\n", m, n, iter, m, n, recur);
    fflush(stdout);
}

UPDATE

Running the command:

g++ -H gcd.cpp -o gcd -g -Wall -Werror -pedantic-errors -fmessage-length=0

I now get this output(it will do the same error for sstream if I switch the order of it and iostream):

. /usr/include/stdio.h
.. /usr/include/sys/cdefs.h
... /usr/include/sys/_symbol_aliasing.h
... /usr/include/sys/_posix_availability.h
.. /usr/include/Availability.h
... /usr/include/AvailabilityInternal.h
.. /usr/include/_types.h
... /usr/include/sys/_types.h
.... /usr/include/machine/_types.h
..... /usr/include/i386/_types.h
.... /usr/include/sys/_pthread/_pthread_types.h
.. /usr/include/sys/_types/_va_list.h
.. /usr/include/sys/_types/_size_t.h
.. /usr/include/sys/_types/_null.h
.. /usr/include/sys/stdio.h
.. /usr/include/sys/_types/_off_t.h
.. /usr/include/sys/_types/_ssize_t.h

Answer 1

You'll want to make sure that you have the Xcode command line tools installed. From the terminal run:

xcode-select --install

More info: http://tips.tutorialhorizon.com/2015/10/01/xcrun-error-invalid-active-developer-path-library-developer-commandline-tools-missing-xcrun/

Whenever I get stuck trying to figure out what the compiler did in Xcode, I always go to see what the command Xcode used was. In your project go to the Report navigator (should be on the left hand side, far right tab):

Then find the line for the file that you are interested in seeing further:

Click on the little stack of pancakes on the far right to expand: