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C Strings
This header file defines several functions to manipulate C strings and arrays.

Functions
Copying:
memcpy	Copy block of memory (function)
memmove	Move block of memory (function)
strcpy	Copy string (function)
strncpy	Copy characters from string (function)

Concatenation:
strcat	Concatenate strings (function)
strncat	Append characters from string (function)

Comparison:
memcmp	Compare two blocks of memory (function)
strcmp	Compare two strings (function)
strcoll	Compare two strings using locale (function)
strncmp	Compare characters of two strings (function)
strxfrm	Transform string using locale (function)

Searching:
memchr	Locate character in block of memory (function)
strchr	Locate first occurrence of character in string (function)
strcspn	Get span until character in string (function)
strpbrk	Locate character in string (function)
strrchr	Locate last occurrence of character in string (function)
strspn	Get span of character set in string (function)
strstr	Locate substring (function)
strtok	Split string into tokens (function)

Other:
memset	Fill block of memory (function)
strerror	Get pointer to error message string (function)
strlen	Get string length (function)

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if (a=(int)'b') /* esta linea Compara el valor Asscii de 'b' con la variable a pero antes haciend un casting de tipos */
{
    ...
}

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if (a=(int)'b') /* ¿a = b? en Ascci? */
{
    ...
}

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Retorna: Longitud de la cadena.
Parametro 1: Puntero a la cadena.
unsigned long int strlen(char* s)
{
     ...
}

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double  atof(char* string)
/*
    Return: Valor de la cadena.
    Parametro 1: puntero a la cadena a convertir
*/
{   //  By BlackZeroX ( http://Infrangelux.sytes.net/ )
    double n, p;
    int i, s;
    
    /* Salta Blancos */
    for ( i=0; string[i]==' ' || string[i]=='\n' || string[i]=='\t'; i++ );
    
    /* Signo? */
    if ( string[i]=='+' || string[i]=='-' )
        s=(string[i++]=='+') ? 1:-1;
    else
        s=1;
    
    /* Valores enteros */
    for ( n=0 ; string[i]>='0' && string[i]<='9'; i++ )
        n = 10*n+string[i]-'0';
    
    /* Punto Decimal? */
    if (string[i]=='.')
        i++;
    
    /* Valores Decimales */
    for ( p=1 ; string[i]>='0' && string[i]<='9'; i++ )
    {
        n = 10*n+string[i]-'0';
        p *= 10; /* Por cuanto Dividiremos? */
    }
    
    /* Al dividir entre p se obtienen los decimales */
    return s * n / p;
}