C++ :: Read Variables From File

I want my program to read variables from file "input.txt":

Please choose the crystal lattice. Type 1 for BCC, 2 for FCC, and 3 for HCP: 2
Please enter lattice parameter (a): 1
For HCP please enter second lattice parameter (c): 1
Please enter the number of translated cells along X axis: 2
Please enter the number of translated cells along Y axis: 2
Please enter the number of translated cells along Z axis: 2

Moreover, I want program to read only the numbers after colon. How can I do it?

Code:
#include <iostream>#include <fstream> // to read from file
using namespace std;
int main () {
int latticeType;
int dimX, dimY, dimZ; // number of translated cells along each axis
float d; // lattice parameter

[Code] ....