A-M baby

Task/Memory-allocation/C/memory-allocation-1.c

@@ -0,0 +1,18 @@
+#include <stdlib.h>
+
+/* size of "members", in bytes */
+#define SIZEOF_MEMB (sizeof(int))
+#define NMEMB 100
+
+int main()
+{
+  int *ints = malloc(SIZEOF_MEMB*NMEMB);
+  /* realloc can be used to increase or decrease an already
+     allocated memory (same as malloc if ints is NULL) */
+  ints = realloc(ints, sizeof(int)*(NMEMB+1));
+  /* calloc set the memory to 0s */
+  int *int2 = calloc(NMEMB, SIZEOF_MEMB);
+  /* all use the same free */
+  free(ints); free(int2);
+  return 0;
+}

Task/Memory-allocation/C/memory-allocation-2.c

@@ -0,0 +1,17 @@
+int func()
+{
+  int ints[NMEMB]; /* it resembles malloc ... */
+  int *int2;       /* here the only thing allocated on the stack is a pointer */
+  char intstack[SIZEOF_MEMB*NMEMB]; /* to show resemblance to malloc */
+  int2 = (int *)intstack;           /* but this is educative, do not do so unless... */
+
+  {
+    const char *pointers_to_char[NMEMB];
+    /* use pointers_to_char */
+    pointers_to_char[0] = "educative";
+  } /* outside the block, the variable "disappears" */
+
+  /* here we can use ints, int2, intstack vars, which are not seen elsewhere of course */
+
+  return 0;
+}

Task/Memory-allocation/C/memory-allocation-3.c

@@ -0,0 +1,8 @@
+#include <alloca.h>
+int *funcA()
+{
+  int *ints = alloca(SIZEOF_MEMB*NMEMB);
+  ints[0] = 0;                                  /* use it */
+  return ints; /* BUT THIS IS WRONG! It is not like malloc: the memory
+                  does not "survive"! */
+}

Task/Memory-allocation/C/memory-allocation-4.c

@@ -0,0 +1,14 @@
+/* this is global */
+int integers[NMEMB]; /* should be initialized with 0s */
+
+int funcB()
+{
+  static int ints[NMEMB]; /* this is "static", i.e. the memory "survive" even
+                             when the function exits, but the symbol's scope is local */
+  return integers[0] + ints[0];
+}
+
+void funcC(int a)
+{
+  integers[0] = a;
+}