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POnot sure what's going on in this code
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copied!<p>I have some C code, and I'm not quite sure what's going on.</p> <pre><code>#include <stdio.h> #include <stdlib.h> #define DIM1 7 #define DIM2 5 #define RES_SIZE 1000 typedef double stackElementT; typedef struct { stackElementT *contents; int maxSize; int top; int min2; } stackT; void StackInit(stackT *stackP, int maxSize) { stackElementT *newContents; newContents = (stackElementT *)malloc(sizeof(stackElementT)*maxSize); if (newContents == NULL) { fprintf(stderr, "Not enough memory.\n"); exit(1); } stackP->contents = newContents; stackP->maxSize = maxSize; stackP->top = -1; } void StackDestroy(stackT *stackP) { free(stackP->contents); stackP->contents = NULL; stackP->maxSize = 0; stackP->top = -1; } int StackIsEmpty(stackT *stackP) { return stackP->top < 0; } int StackIsFull(stackT *stackP) { return stackP->top >= stackP->maxSize-1; } void StackPush(stackT *stackP, stackElementT element) { if(StackIsFull(stackP)) { fprintf(stderr, "Can't push element: stack is full.\n"); exit(1); } stackP->contents[++stackP->top] = element; } stackElementT StackPop(stackT *stackP) { if(StackIsEmpty(stackP)) { fprintf(stderr, "Can't pop element: stack is empty.\n"); exit(1); } return stackP->contents[stackP->top--]; } int shell(char* s1, int arg) { printf("> "); scanf("%s %d%*c", &s1, &arg); return arg; } int main() { char cmds[DIM1][DIM2] = {{"push"}, {"pop"}, {"add"}, {"ifeq"}, {"jump"}, {"print"}, {"dup"}}; char* s1; int arg; arg = shell(s1, arg); printf("%s\n", &s1); } </code></pre> <p>Input: <code>push 4</code>. It prints <code>J+</code> instead of "push" but prints <code>4</code> normally.</p> <p>It also gives these warnings on compile:</p> <pre><code>stack.c: In function ‘shell’: stack.c:60: warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘char **’ stack.c: In function ‘main’: stack.c:71: warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘char **’ stack.c:65: warning: unused variable ‘cmds’ stack.c:69: warning: ‘arg’ is used uninitialized in this function </code></pre> <p>Can someone please explain?</p>

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