Question

我正在编写一个程序，需要从文本中获取金钱价值，当有＃34; rsd＆＃34;旁边就像："20rsd,100rsd,500rsd.."或

John has 20rsd, Danny has 30rsd. Bill gave 40rsd.

结果：90

我尝试了一些东西，但不知道该怎么做。顺便说一下，这是我的大学考试。

int main()
{
char c,d,f;
int price;
FILE *in;
char rsd[] = {'r','s','d'}; 

in = fopen("moneytext.txt","r");

while(!feof(in))
{
    c = fgetc(in);
    if(c=='r')
    {
        d = fgetc(in);
        if(d == 's')
        {
            f = fgetc(in);
            if(f == 'd')
                printf("%c%c%c",c,d,f); //Prints rsd
        }
    }
}
//printf("%c",fgetc(in));
}

Textfile是这样的：

20.10.2017. John gave me 10rsd and Lisa gave me 30rsd, Danny gave me 50rsd, Nicholas donated 10rsd.

Answer 1

对于每个输入行，您可以递归查找子字符串“rsd”，一旦找到一个：

反向查找数字以获得价格
在当前“rsd”+3

看起来像是：

while(fgets(buf, size, fd) != NULL)
{
    char *start = buf;
    /* search for rsd */
    while(start = strstr(start, "rsd"))
    {
        p = start;

        /* reverse find the start of price */
        while(p > buf && IS_DIGIT(*(p-1)))
        {                
            p--;
        }
        if(p < start)
        {
            while(p < start)
            {
                price = price * 10 + *p - '0';
            }
            /** do something about price here */
        }
        start += 3;
    }
}

Answer 2

代码可以循环查找N个条件中的1个

找到一个数字：累加整数值price。
找到后缀模式中的单个字符匹配：前进到下一个字符。如果找到整个模式，请添加price。
都不是。重置模式和价格。
继续，直到EOF找到。

int main() {
  // Use a string to include \0 to denote when to stop match
  const char *rsd = "rsd";

  FILE *out = fopen("moneytext.txt", "w");
  fputs("123 John has 20rsd, Danny456 has 30rsd. Bill789 gave 40rsd", out);
  fclose(out);

  FILE *in = fopen("moneytext.txt", "r");
  if (in) {
    // fgetc() return an int, typically 1 of 257 different values, char is insufficient.
    int c;
    int sum = 0;
    int price = 0;
    const char *pattern = rsd;
    while ((c = fgetc(in)) != EOF) {
      if (isdigit(c)) {
        price = price * 10 + c - '0';
        pattern = rsd;
      } else if (c == (unsigned char) *pattern) {
        pattern++;
        if (*pattern == '\0') {
          pattern = rsd;
          sum += price;
          price = 0;
        }
      } else {
        pattern = rsd;
        price = 0;
      }
    }
    fclose(in);
    printf("Sum:%d\n", sum);
  }
}

输出

Sum:90

需要额外的代码来处理负数，检测int溢出，FILE错误等。

C编程从文本中获取文本旁边的数字

2 个答案: