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What is the best way to zero out new memory after calling realloc while keeping the initially allocated memory intact? #include <stdlib.h> #include <assert.h> #include <string.h> #include <stdio.h> size_t COLORCOUNT = 4; typedef struct rgb_t { int r; int g; int b; } rgb_t; rgb_t** colors; void addColor(size_t i, int r, int g, int b) { rgb_t* color; if (i >= COLORCOUNT) { // new memory wont be NULL colors = realloc(colors, sizeof(rgb_t*) * i); //something messy like this... //memset(colors[COLORCOUNT-1],0 ,sizeof(rgb_t*) * (i - COLORCOUNT - 1)); // ...or just do this (EDIT) for (j=COLORCOUNT; j<i; j++) { colors[j] = NULL; } COLORCOUNT = i; } color = malloc(sizeof(rgb_t)); color->r = r; color->g = g; color->b = b; colors[i] = color; } void freeColors() { size_t i; for (i=0; i<COLORCOUNT; i++) { printf("%x\n", colors[i]); // can't do this if memory isn't NULL // if (colors[i]) // free(colors[i]); } } int main() { colors = malloc(sizeof(rgb_t*) * COLORCOUNT); memset(colors,0,sizeof(rgb_t*) * COLORCOUNT); addColor(0, 255, 0, 0); addColor(3, 255, 255, 0); addColor(7, 0, 255, 0); freeColors(); getchar(); }

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