script/expr_run

• C

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  #include <expr_run.h>
  #include <stdio.h>
   
  // This example shows how to run an expression once. To see how to parse an 
  // expression and run it multiple times, see the expr_w_vars example.
   
  int main(int argc, char *argv[]) {
      ecs_world_t *world = ecs_init_w_args(argc, argv);
   
      // Declare value that will hold the expression result. Specify that we want
      // the returned value to be of type i32. If the expression type doesn't 
      // match the specified type, it will be casted.
      int32_t result = 0;
      ecs_value_t result_value = {
          .type = ecs_id(ecs_i32_t),
          .ptr = &result
      };
   
      // Run the expression. If the operation is successful it returns a pointer
      // to the character after the last parsed token.
      if (ecs_expr_run(world, "10 + 20", &result_value, NULL) == NULL) {
          printf("expression failed to run\n");
          return -1;
      }
   
      printf("result = %d\n", result);
   
      return ecs_fini(world);
   
      // Output
      //  result = 30
  }