ex7_7.c

自己做的常用库和实现的数据结构。public domain.

/*
    ex_7_7
    To change the string to the float_number.
*/

float atofloat(string)
char string[];
{
    char temp ;
    float result = 0 , point = 0 ;
    int index = 0 , sign = 1 ;

    if ( string[0] == '-' )
    {
        index = 1 ;
        sign = -1 ;
    }

    while ( (temp = string[ index++ ]) != '\0' )
    {
        if (temp == '.')
            point = 10 ;
        else if (point)
	{
	    result += (temp-'0')/point ;
	    point *= 10 ;
	}
	else 
	{	
		result = result*10 + temp-'0' ;
	}
    }
    return ( sign*result ) ;
}

main ( )
{
    char string[10];
    float value ;

    printf("Number :\n");
    scanf ("%s",string);

    value = atofloat(string);
    printf("\n%f\n",value);
}