中缀表达式转换成后缀表达式

来源：互联网发布：js数组join方法编辑：程序博客网时间：2024/05/17 00:25
/**写一个程序将中缀表达式转换成后缀表达式(后缀表达式不应包括小括号)，该中缀表达式包括+, -, *, /, **(求幂), %, (, ),空格，tab字符, 以及普通整数,要求通过标准输入接收一个长度不超过16M的字符串做为中缀表达式,将转换后的表达式输出到标准输出.转换原则：中缀表达式a + b*c + (d * e + f) * g，其转换成后缀表达式则为a b c * + d e * f  + g * +。转换过程需要用到栈，具体过程如下：1）如果遇到操作数，我们就直接将其输出。2）如果遇到操作符，则我们将其放入到栈中，遇到左括号时我们也将其放入栈中。3）如果遇到一个右括号，则将栈元素弹出，将弹出的操作符输出直到遇到左括号为止。注意，左括号只弹出并不输出。4）如果遇到任何其他的操作符，如（“+”， “*”，“（”）等，从栈中弹出元素直到遇到发现更低优先级的元素(或者栈为空)为止。弹出完这些元素后，才将遇到的操作符压入到栈中。有一点需要注意，只有在遇到" ) "的情况下我们才弹出" ( "，其他情况我们都不会弹出" ( "。也就是说这种操作，" + "的优先级最低，" ( "优先级最高。5）如果我们读到了输入的末尾，则将栈中所有元素依次弹出。参考：http://blog.csdn.net/ssjhust123/article/details/8001651*/#include <stdlib.h>#include <string.h>#include <ctype.h>#include <stdio.h>#include <stack>using namespace std;bool check ( char* input, int size );int InfixToSuffix ( char* , int ) ;int main ( int argc, char* argv[] ){    char *input;    int size = 0;    if ( argc > 1 ) {        for ( int i = 1; i < argc; ++i ) {            // printf ( "参数%d  :  %s   %d\n", i, argv[i], strlen ( argv[i] ) );            size += strlen ( argv[i] );        }        input = ( char * ) calloc ( size, sizeof ( char ) );        int ite = 0;        for ( int i = 1; i < argc; ++i ) {            int len = strlen ( argv[i] );            for ( int j = 0; j < len; ++j ) {                input[ite++] = argv[i][j];            }        }    } else {        printf ( "please input the expression !!!!\n" );return 0;    }    if ( !check ( input, size ) )        return 0;    InfixToSuffix ( input, size );    free ( input );#ifdef _WIN32    system ( "pause" );#endif    return 0;}int prior ( char op ){    if ( op == '+' || op == '-' ) {        return 1;    }    if ( ( op == '*' ) ||         ( op == '/' ) ||         ( op == '%' ) ) {        return 2;    }    if ( op == '#' ) {        return 3;    }    if ( op == '(' ) {        return 0;    }    return 0;}int my_print ( char data ){    if ( data == '#' ) {        printf ( " ** " );    } else {        printf ( " %c ", data );    }    return 0;}bool check ( char* input, int size ){    int i = 0;    for ( ; i < size - 1; i++ ) {        if ( prior ( input[i] ) && prior ( input[i + 1] ) ) {            if ( ( input[i] ) == '*' &&  input[i + 1]  == '*' ) {                if ( input[i - 1] == '*' ) {// '***'                    printf ( "\n\t%c%c%c is invalid input\n", input[i - 1], input[i], input[i + 1] );                    return 0;                }            } else {                printf ( "\n\t%c%c is invalid input\n", input[i], input[i + 1] );                return 0;            }        }    }    return 1;}void compare_operator ( stack<char> & operator_list, int level ){    while ( operator_list.size() ) {        char temp = operator_list.top();        if ( prior ( temp ) > level ) {            my_print ( temp );            operator_list.pop();        } else {            break;        }    }    return;}int InfixToSuffix ( char* input, int size ){    stack <char> store_operator;    printf ( "=============================================================================\n" );    printf ( "Result as follows,\n" );    int i = 0;    if ( input[0] == '-' || input[0] == '+' ) {  // 判断第一个字符 是否是 '-' or '+'，        printf ( "%c", input[0] );        i = 1;    }    // process ..    for ( ; i < size; ++i ) {        char sw = input[i];        if ( isalnum ( sw ) || ( sw == '.' ) ) {            printf ( "%c", sw );            continue;        }        if ( isspace ( sw ) ) {            continue;        }        if ( sw == '(' ) {            store_operator.push ( sw );            printf ( " " );            continue;        }        if ( sw == ')' ) {            if ( !store_operator.size() ) {                printf ( "处理有错误，或输入有错误%d\n", __LINE__ );                return 1;            }            while ( store_operator.size() ) {                char temp = store_operator.top();                store_operator.pop();                if ( temp == '(' ) {                    break;                }                my_print ( temp );            }            continue;        }        if ( sw == '-' || sw == '+') {            char temp = input[i - 1];            if ( temp == '(' || ( temp == '*' && input[i - 2] == '*' ) ) {                printf ( " %c", sw );                temp = input[i + 1];                while ( temp ) { // 输出整个正/负数 （+/-XXX）                    if ( isalnum ( temp ) || ( temp == '.' ) ) {                        printf ( "%c", temp );                    } else {                        break;                    }                    i++;                    if ( ( i + 1 ) >= size ) {                        printf ( "The expression has error!!!!!!!!! \n" );                        return 0;                    } else {                        temp = input[i + 1];                    }                }                continue;            }            compare_operator ( store_operator, 0 );            store_operator.push ( sw );            printf ( " " );            continue;        }        if ( sw == '*' || sw == '/' || sw == '%' ) {            char temp = input[i + 1];            bool flag = false;            if ( temp == '*' ) { // for '**'， use ‘#’ replace ‘**’                i++; //                flag = true;                compare_operator ( store_operator, 2 );            } else {                compare_operator ( store_operator, 1 );            }            if ( flag ) {                store_operator.push ( '#' );            } else {                store_operator.push ( sw );            }            printf ( " " );            continue;        }        if ( sw ) { //            printf ( "\nThe %c is invalid input, please input again!!!!\n", sw );            return 0;        }    }    while ( store_operator.size() ) {        char temp =  store_operator.top();        my_print ( temp );        store_operator.pop();    }    printf ( "\n=============================================================================\n" );    return 0;}
0 0