C language/c++ (data structure) bracket matching test example (stack and queue) (4/7)

Experimental purpose and requirements: Familiar with using the stack to complete the check of whether the brackets match.

Experiment content: Use the stack to complete the parenthesis matching check. Purpose: To master the application of the last-in-first-out principle of the stack in solving practical problems. Content: Input a set of brackets, construct a stack, use the stack to judge whether the input brackets match, and output three different results: match, multiple left brackets, and multiple right brackets. For any number of non-negative decimal numbers entered, print out the octal number equivalent to its value. The specific implementation process: 1. The sequence stack is expressed as an array, which is used to store the parentheses to be input; 2. Distinguish between different situations through different values ​​of the bottom pointer of the stack; 3. Connect the function. 4. Basic requirements: check the occurrence of parentheses; in-depth analysis: check the occurrence of parentheses, square brackets and curly braces at the same time.

Experimental steps and procedures: #include<stdio.h> #include<stdlib.h> typedef struct {       int *base;       int *top;       int size; }sqstack; sqstack initstack() {       sqstack s;       s.base=(int *)malloc(100*sizeof(int));       s.top=s.base;       return s; } sqstack push(sqstack s,int e) {       *(s.top)=e;       s.top++;       return s; } int gettop(sqstack s) {       if(s.base==s.top)       {             return 0;       }       return *(s.top-1); } sqstack pop(sqstack s) {       s.top--;       return s; } void print(sqstack s) {       while(gettop(s)!=0)       {             printf("%d\n",gettop(s));             s=pop(s);       } } int main() {       sqstack s;       char c=' ';       s=initstack();       printf("请输入括号，以#结束\n");       while(c!='#')       {             scanf("%c",&c);             switch (c)             {                   case '(':s=push(s,1);break;                   case '[':s=push(s,2);break;                   case '{':s=push(s,3);break;                   case ')':                        {                              if(gettop(s)==0)                              {                                    printf("多了*）*\n");                                    return 0;                              }                              else if(gettop(s)==1)                              {                                    s=pop(s);                              }                              else                              {                                    printf("括号不匹配!\n");                                    return 0;                              }                                                     };break;                   case ']':                        {                              if(gettop(s)==0)                              {                                    printf("多了*]*\n");                                    return 0;                              }                              else if(gettop(s)==2)                              {                                    s=pop(s);                              }                              else                              {                                    printf("括号不匹配!\n");                                    return 0;                              }                                                     };break;                   case '}':                        {                              if(gettop(s)==0)                              {                                    printf("多了*}*\n");                                    return 0;                              }                              else if(gettop(s)==3)                              {                                    s=pop(s);                              }                              else                              {                                    printf("括号不匹配!\n");                                    return 0;                              }                                                     };break;                   default:break;             }       }       if(s.top==s.base)       {             printf("括号匹配\n");       }       else       {             printf("多了左括号\n");       }       return 0;  }

运行结果：

结果分析与讨论： 1. 我们可以利利用栈的特点即后进先出的特点来实现括号匹配的检验，存储括号字符的数组通过malloc实现动态分配长度，每读入一个括号，若是左括号，则直接进栈，等待相匹配的同类右括号；若读入的是右括号，且与当前栈顶左括号同类型，则二者匹配，将栈顶的左括号弹出，否则属于不合法情况。另外。如果输入序列已经读完，而栈中仍有等待匹配的左括号，或者读入一个右括号，而栈中已无等待匹配的同类型左括号，均属于不匹配的情况。