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Passing a lambda function to a generic function C++


Lambda passed as parameter via std::function specification for type safety.

#include <functional>

long reduce_rec(const long *A, long low, long
high,
                const std::function<long(long,
long)>& op)
{
    long result;
    long n = high - low;
    if (n == 0){
      return 0;
    }

    else if(high - low == 1){
      return A[low];
    }
    else{
       long mid=(low+high)/2;
       long a,b;

       a = reduce_rec(A, low, mid, op);
       b = reduce_rec(A, mid, high, op);
       //result = a + b;
       result = op(a,b);    // lambda call here
    }
    return result;
}


int caller()
{
    auto lambda = [](long a, long b){ return (a +
b) * (a - b); };

    return reduce_rec(nullptr /*your data*/, 10,
1110, lambda);
}

Categories : C++

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