将字符串转换，浮动（不ATOF）用C [英] Converting string, to float (without atof) in C

问题描述

我设计了一个将字符串转换成浮动的功能。
例如45.5= 45.5

我有这这么远。但它似乎并没有工作。请记住，我们不能使用任何C库函数一样的atoi，ATOF甚至战俘对这一问题。

  INT str2float（字符* S）
{
    INT NUM = 0;
    INT DEC = 0;
    双I = 1.0;
    诠释了TEN = 1;
    / *****添加你的code HERE ***** /    为（;！* S ='\\ 0'; S ++）
    {
        如果（* S =='。'）{
            对于（* S ='\\ 0';！小号++）{
                DEC =（月* CONT）+（* S  - '0'）;
                我++;
            }
        }其他{
            NUM =（NUM * CONT）+（* S  - '0'）;
        }    }
    （！; I = 0;我 - ）为{
        10 * = 10;
    }
    DEC = DEC /（TEN）;
    的printf（％D，DEC）;
    NUM + =分解;
    返回NUM;
}
 

解决方案

下面是我的尝试：

 浮动STOF（为const char * S）{
  浮苏亚雷斯= 0，实际上= 1;
  如果（* S ==' - '）{
    小号++;
    事实上= -1;
  };
  对（INT point_seen = 0; * S; S ++）{
    如果（* S =='。'）{
      point_seen = 1;
      继续;
    };
    INT D = * S  - '0';
    如果（d取代; = 0＆放大器;和D＆下; = 9）{
      如果（point_seen）事实上/ = 10.0f;
      苏亚雷斯=苏亚雷斯* 10.0f +（浮点）D;
    };
  };
  返回苏亚雷斯*事实;
};
 

I'm designing a function that will convert a string into a float. e.g. "45.5" = 45.5

I have this so far. But it doesn't seem to work. Keep in mind, we cannot use any C library functions like atoi, atof or even pow for that matter.

int str2float( char *s )
{
    int num = 0;
    int dec = 0;
    double i = 1.0;
    int ten = 1;
    /***** ADD YOUR CODE HERE *****/

    for(; *s != '\0'; s++)
    {
        if (*s == '.'){
            for(; *s != '\0'; s++){
                dec = (dec * CONT) + (*s - '0');
                i++;
            }
        }else{
            num = (num * CONT) + (*s - '0');
        }

    }
    for(;i!=0;i--){
        ten *= 10;
    }
    dec = dec / (ten);
    printf("%d", dec);
    num += dec;
    return num;  
}

解决方案

Here is my try:

float stof(const char* s){
  float rez = 0, fact = 1;
  if (*s == '-'){
    s++;
    fact = -1;
  };
  for (int point_seen = 0; *s; s++){
    if (*s == '.'){
      point_seen = 1; 
      continue;
    };
    int d = *s - '0';
    if (d >= 0 && d <= 9){
      if (point_seen) fact /= 10.0f;
      rez = rez * 10.0f + (float)d;
    };
  };
  return rez * fact;
};

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