如何添加值，因爲它們是字符串？

Question

我已經嘗試使用atoi然後切換它們回到字符串推，我試圖做一個rpn計算器的類，所以推，彈出，尋求和堆棧結構是如何然後需要，但我不能得到它添加整數值。

#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; 
} 

那就是我的一切都那麼遠，如果你注意到這很好的任何其他問題，但我真正想知道的是如何評價這種數據結構的後綴式輸入的一個例子是-e 2 2 A 5 X.

Answer 1

我希望能對您有所幫助。

#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; 
}