micropython/tests/float/float_format.py

# test float formatting

# general rounding
for val in (116, 1111, 1234, 5010, 11111):
    print('%.0f' % val)
    print('%.1f' % val)
    print('%.3f' % val)

# make sure rounding is done at the correct precision
for prec in range(8):
    print(('%%.%df' % prec) % 6e-5)

# check certain cases that had a digit value of 10 render as a ":" character
print('%.2e' % float('9' * 51 + 'e-39'))
print('%.2e' % float('9' * 40 + 'e-21'))

# check a case that would render negative digit values, eg ")" characters
# the string is converted back to a float to check for no illegal characters
float('%.23e' % 1e-80)