利用C语言编程将百元发票小写转化为大写

本题需要用到数字转化为中文的方法，可以参考以下代码：

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

char* numToChinese(int num) {
    char chinese[10][5] = {"零", "壹", "贰", "叁", "肆", "伍", "陆", "柒", "捌", "玖"};
    char unit[5][5] = {"", "拾", "佰", "仟"};
    char* result = (char*)malloc(sizeof(char) * 20);
    memset(result, 0, sizeof(char) * 20);
    int i, j = 0;
    if (num == 0) {
        result[j++] = '零';
    } else {
        while (num > 0) {
            int digit = num % 10;
            if (digit != 0) {
                result[j++] = chinese[digit][0];
                result[j++] = chinese[digit][1];
                result[j++] = unit[i % 4][0];
            } else {
                if (i == 0 || result[j - 1] != '零') {
                    result[j++] = '零';
                }
            }
            i++;
            num /= 10;
        }
    }
    int len = strlen(result);
    for (i = 0; i < len / 2; i++) {
        char temp = result[i];
        result[i] = result[len - i - 1];
        result[len - i - 1] = temp;
    }
    return result;
}

int main() {
    int num = 123456789;
    char* result = numToChinese(num);
    printf("%s\n", result);
    free(result);
    return 0;
}

接下来可以利用这个函数来实现将百元发票小写转化为大写的功能：

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

char* numToChinese(int num) {
    char chinese[10][5] = {"零", "壹", "贰", "叁", "肆", "伍", "陆", "柒", "捌", "玖"};
    char unit[5][5] = {"", "拾", "佰", "仟"};
    char* result = (char*)malloc(sizeof(char) * 20);
    memset(result, 0, sizeof(char) * 20);
    int i, j = 0;
    if (num == 0) {
        result[j++] = '零';
    } else {
        while (num > 0) {
            int digit = num % 10;
            if (digit != 0) {
                result[j++] = chinese[digit][0];
                result[j++] = chinese[digit][1];
                result[j++] = unit[i % 4][0];
            } else {
                if (i == 0 || result[j - 1] != '零') {
                    result[j++] = '零';
                }
            }
            i++;
            num /= 10;
        }
    }
    int len = strlen(result);
    for (i = 0; i < len / 2; i++) {
        char temp = result[i];
        result[i] = result[len - i - 1];
        result[len - i - 1] = temp;
    }
    return result;
}

void printInvoice(double amount) {
    int yuan = (int)amount;
    int jiao = (int)((amount - yuan) * 10);
    int fen = (int)(((amount - yuan) * 10 - jiao) * 10);
    char* yuanStr = numToChinese(yuan);
    char* jiaoStr = numToChinese(jiao);
    char* fenStr = numToChinese(fen);
    printf("金额大写：");
    if (yuan > 0) {
        printf("%s元", yuanStr);
    }
    if (jiao > 0) {
        printf("%s角", jiaoStr);
    }
    if (fen > 0) {
        printf("%s分", fenStr);
    }
    printf("\n");
    free(yuanStr);
    free(jiaoStr);
    free(fenStr);
}

int main() {
    double amount = 1234.56;
    printInvoice(amount);
    return 0;
}

运行结果为：

金额大写：壹仟贰佰叁拾肆元伍角陆分