Is each of the following definitions valid or invalid If any

Is each of the following definitions valid or invalid? If any is invalid state why?

int ivar;

int *iptr

int ivar, *ptr = &ivar;

float fvar;

int *ivar = &fvar;

int nums [50], *iptr = nums;

int *iptr = &ivar;

int ivar;

Solution

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int ivar;

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Answer:
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   Valid

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Explanation:
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   int ivar; is a valid defination , it states declaring a ivar variable of type
int.

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int *iptr;

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Answer:
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   Valid

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Explanation:
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   int *iptr; is a valid defination, it states declaring *iptr variable of type integer pointer.
  
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int ivar, *ptr = &ivar;

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Answer:
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   Valid

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Explanation:
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   int ivar, *ptr = &ivar; is a valid defincation.
  
   It states ivar variable of type integer and
   *ptr of type integer pointer holding address of ivar variable.
  
   For Example: if ivar = 5 then *ptr value also 5. Since *ptr is holding the address of ivar.
  
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float fvar;

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Answer:
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   Valid

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Explanation:
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   float fvar; is valid defination. it states declaring fvar variable of type float.
  
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int *ivar = &fvar;

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Answer:
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   Invalid

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Explanation:
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   int *ivar = &fvar; is a invalid defination, Since here *ivar pointer of type integer.
   Which can not hold the address of type float. hence the defination is invalid.
  
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int nums [50], *iptr = nums;

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Answer:
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   Valid

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Explanation:
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   int nums [50], *iptr = nums; is valid defination, Since nums is of type integer array
   and *iptr of type integer pointer, Which is holding starting address of array.
  
   For Example: if nums [2] ={1,2} then *iptr value printed is 1. Since *iptr is holding the base address of
   integer array nums.
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int *iptr = &ivar;

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Answer:
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   Valid

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Explanation:
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   int *iptr = &ivar; is valid defination since it is holding the address of the ivar of type integer.
   Consider initial declarion for ivar is int ivar;
  
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int ivar;

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Answer:
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   Valid

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Explanation:
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   int ivar; is a valid defination , it states declaring a ivar variable of type
int.

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