Add relu.cpp example in test/neura/for_loop

test/neura/for_loop/relu.cpp

@@ -0,0 +1,40 @@
+#include <stdio.h>
+
+#define N 32
+
+int input[N] = {
+  1, -1, 2, -3, 4, -5, 6, -7,
+  8, -9, 10, -11, 12, -13, 14, -15,
+  16, -17, 18, -19, 20, -21, 22, -23,
+  24, -25, 26, -27, 28, -29, 30, -31
+};
+
+int output[N];
+
+void kernel(float input[], float output[]);
+
+int main(){
+  //init output
+  for(int i = 0; i < N; i++){
+    output[i] = 0;
+  }
+
+  kernel(intput, output);
+
+  //print outputs
+  for(int i = 0; i < N; i++){
+    print("output[%d] = %f\n", i, output[i]); 
+  }
+
+  return 0;
+}
+
+void kernel(int input[], int output []){
+  for(int i = 0; i < N; ++i){
+    if(input[i] > 0){
+      output[i] += input[i];
+    } else {
+      output[i] += 0;
+    }
+  }
+}