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  1. //
  2. // a toy calculator in reverse Polish notation
  3. // similar to dc in Unix
  4. // this illustrates the stack pointer idioms
  5. // *sp++ and so on
  6. // Hayo Thielecke 12.1.2014
  7.  
  8. #include <stdio.h>
  9. #include <string.h>
  10. #include <stdlib.h>
  11. #include <iostream>
  12.  
  13. template<typename T>
  14. class stackArray {
  15. public:
  16.  
  17. 	const int stacksize = 100;
  18.  
  19. 	T stack[100];
  20. 	T *sp;
  21.  
  22. 	// invariant: sp points to first free element
  23.  
  24. 	stackArray<T>() {
  25. 	  sp = stack; // Here we go.
  26. 	};
  27.  
  28. 	~stackArray<T>() {
  29. 	  //delete [] stack;	
  30. 	 // free(stack);
  31. 	    sp = NULL;
  32. 	};
  33.  
  34.  
  35. 	void push(T n)
  36. 	{
  37. 	    if (sp < stack + stacksize - 1) {
  38. 		*sp++ = n;
  39. 	    } else {
  40. 		fprintf(stderr, "Stack overflow!\n\n");
  41. 		exit(1);
  42. 	    }
  43. 	}
  44.  
  45. 	T pop()
  46. 	{
  47. 	    if (sp > stack) {
  48. 		return *--sp;
  49. 	    } else {
  50. 		fprintf(stderr, "Stack underflow!\n\n");
  51. 		exit(1);
  52. 	    }
  53. 	}
  54.  
  55. 	int isempty() {
  56. 	    if (sp <= stack) {
  57. 		return 1;
  58. 	    }
  59. 	    return 0;
  60. 	}
  61.  
  62. 	void printstack()
  63. 	{
  64.     		int *p = sp - 1;
  65.     		printf("\nStack is: ");
  66.    		while (p >= stack)
  67.         	printf("%6d", *p--);
  68.     		printf("\n\n");
  69. 	}
  70.  
  71. 	void applytoall(void (*func) (T&))
  72. 	{
  73.    		 T *p = sp - 1;
  74.    		 while (p >= stack)
  75.    		    func(*p--);
  76.    		 printf("\n");
  77. 	}
  78.  
  79.  
  80.  
  81. };
  82.  
  83.  
  84. void plusone(int &p)
  85. 	{
  86. 		p = p + 1;
  87. 	}
  88.  
  89. int main() {
  90. 	stackArray<int> g;
  91. 	g.push(1);
  92. 	g.push(2);
  93. 	g.push(3);
  94. 	int empty = g.isempty();
  95. 	std::cout << "HEY" << empty <<  "\n";
  96. 	g.printstack();
  97. 	g.pop();
  98. 	g.printstack();
  99. 	g.applytoall(plusone);
  100. 	g.printstack();
  101. }
  102.  
  103.  
  104.  
Success #stdin #stdout 0s 3140KB
comments (?)
stdin 
Standard input is empty
stdout 
HEY0

Stack is:      3     2     1


Stack is:      2     1



Stack is:      3     2
https://ideone.com/XHamSU
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
public

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