Overview
Python integers (int) support arbitrary precision - they can represent integers of any size limited only by available memory.
Type Object
The Python int type.
Type Checking
int PyLong_Check(PyObject *p)
int PyLong_CheckExact(PyObject *p)
Creating Integers
From C Types
PyObject* PyLong_FromLong(long v)
PyObject* PyLong_FromUnsignedLong(unsigned long v)
PyObject* PyLong_FromLongLong(long long v)
PyObject* PyLong_FromUnsignedLongLong(unsigned long long v)
PyObject* PyLong_FromSize_t(size_t v)
PyObject* PyLong_FromSsize_t(Py_ssize_t v)
PyObject* PyLong_FromDouble(double v)
PyObject *num = PyLong_FromLong(42);
if (num == NULL)
return PyErr_NoMemory();
return num;
From Strings
PyObject* PyLong_FromString(const char *str, char **pend, int base)
PyObject *num = PyLong_FromString("ff", NULL, 16); // Returns 255
Converting to C Types
long PyLong_AsLong(PyObject *obj)
unsigned long PyLong_AsUnsignedLong(PyObject *obj)
long long PyLong_AsLongLong(PyObject *obj)
unsigned long long PyLong_AsUnsignedLongLong(PyObject *obj)
Py_ssize_t PyLong_AsSsize_t(PyObject *obj)
double PyLong_AsDouble(PyObject *obj)
PyErr_Occurred())
Example:
long value = PyLong_AsLong(obj);
if (value == -1 && PyErr_Occurred()) {
// Handle overflow or type error
return NULL;
}
printf("Value: %ld\\n", value);
With Overflow Detection
long PyLong_AsLongAndOverflow(PyObject *obj, int *overflow)
Set to -1, 0, or 1 indicating underflow, success, or overflow
int overflow;
long value = PyLong_AsLongAndOverflow(obj, &overflow);
if (overflow != 0) {
if (overflow < 0)
printf("Value too small for long\\n");
else
printf("Value too large for long\\n");
return NULL;
}
Complete Example
static PyObject* add_integers(PyObject *self, PyObject *args) {
PyObject *a, *b;
long val_a, val_b, result;
if (!PyArg_ParseTuple(args, "OO", &a, &b))
return NULL;
// Check types
if (!PyLong_Check(a) || !PyLong_Check(b)) {
PyErr_SetString(PyExc_TypeError, "Arguments must be integers");
return NULL;
}
// Convert to C long
val_a = PyLong_AsLong(a);
if (val_a == -1 && PyErr_Occurred())
return NULL;
val_b = PyLong_AsLong(b);
if (val_b == -1 && PyErr_Occurred())
return NULL;
// Perform operation
result = val_a + val_b;
// Return as Python int
return PyLong_FromLong(result);
}
See Also
