c - 由于它们是字符串，我将如何添加值？

Question

我已经尝试过使用atoi，然后将它们切换回字符串进行推送，我正在尝试为类制作一个 rpn 计算器，因此推送、弹出、查找和堆栈结构就是接下来需要的是，但我无法让它添加整数值。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

struct stack
{
  const char * data;
  struct stack *bottom;
};

struct stack * push(struct stack *stk,const char * x)
{
    struct stack *nstk = (struct stack *)malloc(sizeof(struct stack));

    nstk->data = x;
    nstk->bottom = stk;

    return nstk;
}


const char * peek(struct stack *stk)
{
    if(stk -> data)
      return stk->data;
    else
      return("Stack is empty");
}

struct stack *pop(struct stack *stk)
{
    struct stack *tmp;

    tmp = stk->bottom;
    stk->bottom = NULL;
    free(stk);

    return tmp;
}

FILE * input_from_args(int argc,const char *argv[])
{
    if(strcmp(argv[1],"-e") != 0 && strcmp(argv[1],"-c") != 0 && strcmp(argv[1],"-g") != 0)
    {
      printf("Option %s is not supported \n", argv[1]);
      exit(0);
    }

     else
    {
        return stdin;
    }
}
void evaluate(struct stack * equation)
{
     int op;
     int op2;
     int ans;

     if(strcmp("A",equation->data) == 0)
      {
      op = (int)pop(equation)-> data;
      op2 = (int)pop(equation)-> data;
      ans = op + op2;
      printf("%i",ans);
      }
}

void convert(struct stack  * equation)
{
}

void other (struct stack * equation)
{

}


int main(int argc,const char *argv[])
{
  FILE *src = input_from_args(argc, argv);

    if (src == NULL)
    {
        printf("%s", "Invalid Source");
        exit(EXIT_FAILURE);
    }

    struct stack * equation = NULL;

    int i;
    for(i=2; i <= argc; i++)
    {
      equation = push(equation,argv[i]);
    }

    if(strcmp(argv[1],"-e") == 0)
    {
      evaluate(equation);
    }
    else if(strcmp(argv[1],"-c") == 0)
    {
      convert(equation);
    }
    else if(strcmp(argv[1],"-g") == 0)
    {
      other(equation);
    }

    return EXIT_SUCCESS;
}

这就是到目前为止我所拥有的一切，如果您注意到任何其他问题也没关系，但我真正想知道的是如何使用此数据结构评估后缀方程(输入示例为 -e 2 2 A 5 X)。

Answer 1

希望对您有所帮助。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

typedef int DataType;

DataType cnv(const char *s){
    return atoi(s);
}

#define PRN_DATA "%d"

typedef struct stack {
    DataType data;
    struct stack *bottom;
} Stack;

void push(Stack **stk, DataType x){
    struct stack *nstk = malloc(sizeof(Stack));

    nstk->data = x;
    nstk->bottom = *stk;

    *stk = nstk;
}

int empty(Stack *stk){
    return stk == NULL;
}

DataType pop(Stack **stk){
    struct stack *tmp = *stk;
    if(empty(*stk)){
        printf("empty stack\n");
        exit(EXIT_FAILURE);
    }
    DataType ret = tmp->data;

    *stk = (*stk)->bottom;
    free(tmp);

    return ret;
}

char input_from_args(int *argc, const char ***argv){
    if( *argc < 2 || (*argv)[1][0] != '-' || (*argv)[1][1] == '\0'){
        printf("Option is not specified\n");
        exit(EXIT_FAILURE);
    }
    char op = (*argv)[1][1];
    if((*argv)[1][2] != '\0' || op != 'e'  && op != 'c' && op != 'g'){
        printf("Option %s is not supported \n", (*argv)[1]);
        exit(EXIT_FAILURE);
    }
    *argv = &(*argv)[2];
    *argc -= 2;
    return op;
}

void evaluate(int argc, const char **argv){
    struct stack *s = NULL;
    int i;
    DataType v1, v2;
    for(i = 0; i < argc; ++i){
        switch(*argv[i]){
        case 'A':
            v2 = pop(&s);
            v1 = pop(&s);
            push(&s, v1 + v2);
            break;
        case 'S':
            v2 = pop(&s);
            v1 = pop(&s);
            push(&s, v1 - v2);
            break;
        case 'X':
            v2 = pop(&s);
            v1 = pop(&s);
            push(&s, v1 * v2);
            break;
        case 'D':
            v2 = pop(&s);
            v1 = pop(&s);
            push(&s, v1 / v2);
            break;
        default:
            push(&s, cnv(argv[i]));
        }
    }
    printf(PRN_DATA "\n", pop(&s));
    if(!empty(s)){
        printf("data remains in the stack\n");
        exit(EXIT_FAILURE);
    }
}

void convert(int argc, const char **argv){
}

void other (int argc, const char **argv){
}

int main(int argc, const char **argv){
    switch(input_from_args(&argc, &argv)){
    case 'e':
        evaluate(argc, argv);
        break;
    case 'g':
        other(argc, argv);
        break;
    case 'c':
        convert(argc, argv);
        break;
    }

    return EXIT_SUCCESS;
}