Just another update

Task/Create-a-two-dimensional-array-at-runtime/C/create-a-two-dimensional-array-at-runtime-2.c

@@ -1,20 +1,116 @@
-#include <stdio.h>
-#include <stdlib.h>
-int main(int argc, char **argv)
-{
-   int user1 = 0, user2 = 0;
-   int *a1, **array, row;
+/*
+  assume this file is c.c ,
+  compile and run on linux: cc -Wall -g -DCOMPILE_EXAMPLE c.c -lm -o c && ./c
+*/
 
-   printf("Enter two integers.  Space delimited, please:  ");
-   scanf("%d %d",&user1, &user2);
+#include<stdlib.h>
+#include<stdio.h>
 
-   a1 = malloc(user1*user2*sizeof(int));
-   array = malloc(user2*sizeof(int*));
-   for (row=0; row<user1; row++) array[row]=a1+row*user2;
-
-   array[user1/2][user2/2] = user1 + user2;
-   printf("array[%d][%d] is %d\n",user1/2,user2/2,array[user1/2][user2/2]);
-   free(array);
-   free(a1);
-   return 0;
+static void error(int status, char*message) {
+  fprintf(stderr,"\n%s\n",message);
+  exit(status);
 }
+
+static void*dwlcalloc(int n,size_t bytes) {
+  void*rv = (void*)calloc(n,bytes);
+  if (NULL == rv)
+    error(1, "memory allocation failure");
+  return rv;
+}
+
+void*allocarray(size_t rank,size_t*shape,size_t itemSize) {
+  /*
+     Allocates arbitrary dimensional arrays (and inits all pointers)
+     with only 1 call to malloc.  Lambert Electronics, USA, NY.
+     This is wonderful because one only need call free once to deallocate
+     the space.  Special routines for each size array are not need for
+     allocation of for deallocation.  Also calls to malloc might be expensive
+     because they might have to place operating system requests.  One call
+     seems optimal.
+  */
+  size_t size,i,j,dataSpace,pointerSpace,pointers,nextLevelIncrement;
+  char*memory,*pc,*nextpc;
+  if (rank < 2) {
+    if (rank < 0)
+      error(1,"invalid negative rank argument passed to allocarray");
+    size = rank < 1 ? 1 : *shape;
+    return dwlcalloc(size,itemSize);
+  }
+  pointerSpace = 0, dataSpace = 1;
+  for (i = 0; i < rank-1; ++i)
+    pointerSpace += (dataSpace *= shape[i]);
+  pointerSpace *= sizeof(char*);
+  dataSpace *= shape[i]*itemSize;
+  memory = pc = dwlcalloc(1,pointerSpace+dataSpace);
+  pointers = 1;
+  for (i = 0; i < rank-2; ) {
+    nextpc = pc + (pointers *= shape[i])*sizeof(char*);
+    nextLevelIncrement = shape[++i]*sizeof(char*);
+    for (j = 0; j < pointers; ++j)
+      *((char**)pc) = nextpc, pc+=sizeof(char*), nextpc += nextLevelIncrement;
+  }
+  nextpc = pc + (pointers *= shape[i])*sizeof(char*);
+  nextLevelIncrement = shape[++i]*itemSize;
+  for (j = 0; j < pointers; ++j)
+    *((char**)pc) = nextpc, pc+=sizeof(char*), nextpc += nextLevelIncrement;
+  return memory;
+}
+
+#ifdef COMPILE_EXAMPLE
+
+#include<string.h>
+#include<math.h>
+
+#define Z 5
+#define Y 10
+#define X 39
+
+#define BIND(A,L,H) ((L)<(A)?(A)<(H)?(A):(H):(L))
+
+void p_char(void*pv) {
+  char s[3];
+  int i = 0;
+  s[i++] = ' ', s[i++] = *(char*)pv, s[i++] = 0;
+  fputs(s, stdout);
+}
+
+void display(void*a,size_t rank,size_t*shape,void(*f)(void*)) {
+  int i;
+  if (0 == rank)
+    (*f)(a);
+  else if (1 == rank) {
+    for (i = 0; i < *shape; ++i)
+      (*f)(a+i);
+    putchar('\n');
+  } else {
+    for (i = 0; i < *shape; ++i)
+      display(((void**)a)[i], rank-1, shape+1, f);
+    putchar('\n');
+  }
+}
+
+int main() {			/* character cell 3D graphics.  Whoot */
+  char***array;
+  float x,y,z;
+  size_t rank, shape[3], i, j, k;
+  rank = 0;
+  shape[rank++] = Z, shape[rank++] = Y, shape[rank++] = X;
+  array = allocarray(rank, shape, sizeof(char));
+  memset(**array, ' ', X*Y*Z*(sizeof(***array))); /* load the array with spaces */
+  for (i = 0; i < X; ++i) {
+    x = i/(float)X;
+    for (j = 0; j < Y; ++j) {
+      y = j/(float)X;
+      z = x*y*(4*M_PI);
+      z = 5.2*(0.5+(0.276765 - sin(z)*cos(z)*exp(1-z))/0.844087); /* a somewhat carefully designed silly function */
+      /* printf("%g %g %g\n", x, y, z); */
+      k = (int)z;
+      array[BIND(k, 0, Z-1)][j][i] = '@'; /* BIND ensures a valid index  */
+    }
+  }
+  display(array, rank, shape, p_char);
+  puts("\nIt is what it is.");
+  free(array);
+  return EXIT_SUCCESS;
+}
+#endif

Task/Create-a-two-dimensional-array-at-runtime/C/create-a-two-dimensional-array-at-runtime-3.c

@@ -2,26 +2,18 @@
 #include <stdlib.h>
 int main(int argc, char **argv)
 {
-   int user1 = 0;
-   int space_needed;
-   int *a1, **array;
-   int row, col;
+   int user1 = 0, user2 = 0;
+   int *a1, **array, row;
 
-   printf("Enter size of array:  ");
-   scanf("%d",&user1);
+   printf("Enter two integers.  Space delimited, please:  ");
+   scanf("%d %d",&user1, &user2);
 
-   space_needed = (user1+1)*user1/2;
-   a1 = malloc(space_needed);
+   a1 = malloc(user1*user2*sizeof(int));
    array = malloc(user1*sizeof(int*));
-   for (row=0,offset=0; row<user1; offset+=(user1-row), row++) {
-      array[row]=a1+offset-row;
-      for (col=row; col<user1; col++)
-          array[row][col] = 1+col-row;
-   }
-   for (row=0; row<user1; row++)
-      printf("%d ", array[row][user1-1]);
-   printf("\n");
+   for (row=0; row<user1; row++) array[row]=a1+row*user2;
 
+   array[user1/2][user2/2] = user1 + user2;
+   printf("array[%d][%d] is %d\n",user1/2,user2/2,array[user1/2][user2/2]);
    free(array);
    free(a1);
    return 0;

Task/Create-a-two-dimensional-array-at-runtime/C/create-a-two-dimensional-array-at-runtime-4.c

@@ -1,18 +1,28 @@
 #include <stdio.h>
-#include <alloca.h>
+#include <stdlib.h>
 int main(int argc, char **argv)
 {
-   int user1 = 0, user2 = 0;
-   int *a1, **array, row;
+   int user1 = 0;
+   int space_needed;
+   int *a1, **array;
+   int row, col, offset;
 
-   printf("Enter two integers.  Space delimited, please:  ");
-   scanf("%d %d",&user1, &user2);
+   printf("Enter size of array:  ");
+   scanf("%d",&user1);
 
-   a1 = alloca(user1*user2*sizeof(int));
-   array = alloca(user1*sizeof(int*));
-   for (row=0; row<user1; row++) array[row]=a1+row*user2;
+   space_needed = (user1+1)*user1/2;
+   a1 = malloc(space_needed * sizeof(*a1));
+   array = malloc(user1 * sizeof(*array));
+   for (row=0,offset=0; row<user1; offset+=(user1-row), row++) {
+      array[row]=a1+offset-row;
+      for (col=row; col<user1; col++)
+          array[row][col] = 1+col-row;
+   }
+   for (row=0; row<user1; row++)
+      printf("%d ", array[row][user1-1]);
+   printf("\n");
 
-   array[user1/2][user2/2] = user1 + user2;
-   printf("array[%d][%d] is %d\n",user1/2,user2/2,array[user1/2][user2/2]);
+   free(array);
+   free(a1);
    return 0;
 }

Task/Create-a-two-dimensional-array-at-runtime/C/create-a-two-dimensional-array-at-runtime-5.c

@@ -0,0 +1,18 @@
+#include <stdio.h>
+#include <alloca.h>
+int main(int argc, char **argv)
+{
+   int user1 = 0, user2 = 0;
+   int *a1, **array, row;
+
+   printf("Enter two integers.  Space delimited, please:  ");
+   scanf("%d %d",&user1, &user2);
+
+   a1 = alloca(user1*user2*sizeof(int));
+   array = alloca(user1*sizeof(int*));
+   for (row=0; row<user1; row++) array[row]=a1+row*user2;
+
+   array[user1/2][user2/2] = user1 + user2;
+   printf("array[%d][%d] is %d\n",user1/2,user2/2,array[user1/2][user2/2]);
+   return 0;
+}