Why do I get an "undeclared" error in the main function?

Question

My function won't compile as it keeps saying "x is undeclared" in the main function (can't be modified), what am I doing wrong?

int main(){
  printf("\nsquare root test 1: enter a number\n");
  scanf("%f",&x);
  printf("root(%.2f) = %.4f\n", x, squareRoot(x, .001));

  getchar();
  return 0;
}

For completeness, this is the implementation of the squareRoot function:

float squareRoot(float value, float error){
    float estimate;
    float quotient;
    estimate = 1;
    float difference = abs(value - estimate * estimate);
    while (difference > error){
        quotient = value/estimate;
        estimate = (estimate + quotient)/2;
        difference = abs(value - estimate * estimate);
    }
    return difference;
}

Civa · Answer 1 · 2013-03-16T08:07:09.183

1

declare x first to use it inside main function

float x;

Like this with in the scope or you can declare globally

int main(){
  float x;
  printf("\nsquare root test 1: enter a number\n");
  scanf("%f",&x);
  printf("root(%.2f) = %.4f\n", x, squareRoot(x, .001));

  getchar();
  return 0;
}

edited Mar 16 '13 at 08:07

answered Mar 16 '13 at 05:12

Civa

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Also, if `main()` cannot be modified, then `x` needs to be declared at file scope. – Mar 16 '13 at 05:57
@H2CO3 what do you mean by `main()` can't be modified? – SomeWittyUsername Mar 16 '13 at 08:03
@icepack Read the question. "in the main function (can't be modified), [...]" – Mar 16 '13 at 08:23

score 1 · Answer 2 · answered Mar 16 '13 at 07:56

1

If x cannot be declared in the main function, then declare it in a global scope,

float x;

int main( ) {
  ...
}

answered Mar 16 '13 at 07:56

Rontogiannis Aristofanis

8,883
8
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score 0 · Answer 3 · answered Mar 16 '13 at 08:02

0

int main(){
  float x ; /* You missed this :-D */
  printf("\nsquare root test 1: enter a number\n");
  scanf("%f",&x);
  printf("root(%.2f) = %.4f\n", x, squareRoot(x, .001));

  getchar();
  return 0;
}

answered Mar 16 '13 at 08:02

Abhineet

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Why do I get an "undeclared" error in the main function?

3 Answers3

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