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  1. #include<stdio.h>
  2. #include<stdlib.h>
  3.  
  4. int n; //initial no. of integers in array
  5. int *list; //pointer to the array of integers
  6. int *MergeSort(int *A, int x, int y); //definition, return type is pointer to integer array
  7.  
  8.  
  9. void main()
  10. {
  11. 	printf("Enter the no. of integers in the array: ");
  12. 	scanf("%d",&n);
  13.  
  14. 	list=(int *)malloc(n*sizeof(int));
  15.  
  16. 	for(int i=0;i<n;i++) //taking input
  17. 	{	
  18. 		printf("\nEnter a no.: ");
  19. 		scanf("%d",&list[i]);
  20. 	}
  21.  
  22. 	MergeSort(list,0,n-1); //calling MergeSort on list from index 0 to index n-1
  23.  
  24. 	for(int i=0;i<n;i++) //printing output
  25. 	{	
  26. 		printf("%d ",list[i]);
  27. 	}
  28.  
  29. }
  30.  
  31. int *MergeSort(int *A, int x, int y) //declaration
  32. {
  33. 	if(x==y) //base case, return the 1-element array itself
  34. 	{
  35. 		return A;
  36. 	}
  37.  
  38. 	else
  39. 	{
  40. 		int size=1+y-x; //total no. of elements
  41. 		int half=(x+y)/2; //halving the array
  42.  
  43. 		MergeSort(A, x, half);	//calling MergeSort on 1st half of array
  44. 		MergeSort(A, half+1, y);		//calling MergeSort on 2nd half of array
  45.  
  46.  
  47. 		int *C;		//pointer to 3rd array
  48. 		C=(int *)malloc(size*sizeof(int));
  49. 		int j=x; 			//indicator for first half
  50. 		int k=half;			//indicator for 2nd half
  51. 		int i=0;			//indicator for 3rd array
  52.  
  53.  
  54. 		while((j<=half)||(k<=y))			//till all the elements from either half are not exhausted
  55. 		{
  56. 			if(A[j]<=A[k])					//if element of first half is smaller, put that in C
  57. 			{
  58. 				C[i]=A[j];
  59. 				j++;
  60. 			}
  61. 			else					//otherwise put element of second half in C
  62. 			{
  63. 				C[i]=A[k];
  64. 				k++;
  65. 			}
  66. 			i++;				//increment indicator for C
  67. 		}
  68.  
  69.  
  70. 		if(j==(half+1)) 		//if first half is finished
  71. 		{
  72. 			while(i<size) 		//transfer all elements of second half in C
  73. 			{
  74. 				C[i]=A[k];
  75. 				i++;
  76. 				k++;
  77. 			}
  78. 		}
  79. 		else if(k==(y+1)) //if second half is finished
  80. 		{
  81. 			while(i<size) //transfer all elements of 1st half in C
  82. 			{
  83. 				C[i]=A[j];
  84. 				i++;
  85. 				j++;
  86. 			}
  87. 		}
  88.  
  89.  
  90.  
  91. 		return C; //return C
  92. 	}
  93.  
  94. }
Compilation error #stdin compilation error #stdout 0s 0KB
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stdin
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Standard input is empty
compilation info 
prog.c:9:6: warning: return type of ‘main’ is not ‘int’ [-Wmain]
 void main()
      ^
prog.c: In function ‘main’:
prog.c:16:2: error: ‘for’ loop initial declarations are only allowed in C99 mode
  for(int i=0;i<n;i++) //taking input
  ^
prog.c:16:2: note: use option -std=c99 or -std=gnu99 to compile your code
prog.c:24:10: error: redefinition of ‘i’
  for(int i=0;i<n;i++) //printing output
          ^
prog.c:16:10: note: previous definition of ‘i’ was here
  for(int i=0;i<n;i++) //taking input
          ^
prog.c:24:2: error: ‘for’ loop initial declarations are only allowed in C99 mode
  for(int i=0;i<n;i++) //printing output
  ^
stdout
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Standard output is empty
https://ideone.com/utEzoq
language:
C (gcc 8.3)
created:
10 years ago
visibility:
public

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