课内上机实验3——括号匹配（栈）

#include <stdio.h>
char a[1000];
int top = 0;//top points at the first empty element
void put_stack(char c)
{
    a[top++] = c;
}
char pop_stack( )
{
    char pop = a[top-1];
    top--;
    return pop;
}
int bracket_pair(char c)
{
    switch (c) {
        case ‘)‘:
            if (pop_stack() == ‘(‘)
                return 1;
            break;
        case ‘]‘:
            if (pop_stack() == ‘[‘)
                return 1;
            break;
        case ‘}‘:
            if (pop_stack() == ‘{‘)
                return 1;
            break;
    }
    return 0;
}
int main(int argc, const char * argv[])
{
    int flag=1;
    char c;
    c = getchar();
    while (c != ‘\n‘) {
        switch (c) {
            case ‘(‘:;
            case ‘[‘:;
            case ‘{‘:
                put_stack(c);break;
            case ‘)‘:;
            case ‘]‘:;
            case ‘}‘:
                flag = bracket_pair(c);
        }
        if (flag==0)
            break;
        
        c = getchar();
    }
    if (flag==1&&top==0) {
        printf("yes");
    }else{
        printf("no");
    }
    return 0;
}