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Annotation of 42BSD/ingres/source/gutil/atoi.c, revision 1.1.1.1

1.1       root        1: # include      <ingres.h>
                      2: # include      <sccs.h>
                      3: 
                      4: SCCSID(@(#)atoi.c      7.1     2/5/81)
                      5: 
                      6: /*
                      7: **  ASCII CHARACTER STRING TO INTEGER CONVERSION
                      8: **
                      9: **     `a' is a pointer to the character string, `i' is a
                     10: **     pointer to the word which is to contain the result.
                     11: **     The integer is either 16-bit or 32-bit depending upon
                     12: **     the natural word length of the machine.
                     13: **
                     14: **     The return value of the function is:
                     15: **             zero:   succesful conversion; `i' contains the integer
                     16: **             +1:     numeric overflow; `i' is unchanged
                     17: **             -1:     syntax error; `i' is unchanged
                     18: **
                     19: **     A valid string is of the form:
                     20: **             <space>* [+-] <space>* <digit>* <space>*
                     21: */
                     22: 
                     23: atoi(a, i)
                     24: register char  *a;
                     25: int    *i;
                     26: {
                     27: # ifdef PDP11
                     28:        int             sign;           /* flag to indicate the sign */
                     29:        register int    x;              /* holds the integer being formed */
                     30:        register char   c;
                     31: 
                     32:        sign = 0;
                     33:        /* skip leading blanks */
                     34:        while (*a == ' ')
                     35:                a++;
                     36:        /* check for sign */
                     37:        switch (*a)
                     38:        {
                     39: 
                     40:          case '-':
                     41:                sign = -1;
                     42: 
                     43:          case '+':
                     44:                while (*++a == ' ');
                     45:        }
                     46: 
                     47:        /* at this point everything had better be numeric */
                     48:        x = 0;
                     49:        while ((c = *a) <= '9' && c >= '0')
                     50:        {
                     51:                if (x > 3276 || (x == 3276 && c > '7'))
                     52:                        return (1);             /* overflow */
                     53:                x = x * 10 + c - '0';
                     54:                a++;
                     55:        }
                     56: 
                     57:        /* eaten all the numerics; better be all blanks */
                     58:        while (c = *a++)
                     59:                if(c != ' ')                    /* syntax error */
                     60:                        return (-1);
                     61:        *i = sign ? -x : x;
                     62:        return (0);             /* successful termination */
                     63: # else
                     64:        return (atol(a, i));
                     65: # endif
                     66: }

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