tests/float/float_format.py

# test float formatting

# general rounding
for val in (116, 1111, 1234, 5010, 11111):
    print("Test on %d / 1000:" % val)
    for fmt in ("%.5e", "%.3e", "%.1e", "%.0e", "%.3f", "%.1f", "%.0f", "%.3g", "%.1g", "%.0g"):
        print(fmt, fmt % (val / 1000))

# make sure round-up to the next unit is handled properly
for val in range(4, 9):
    divi = 10**val
    print("Test on 99994 / (10 ** %d):" % val)
    for fmt in ("%.5e", "%.3e", "%.1e", "%.0e", "%.3f", "%.1f", "%.0f", "%.3g", "%.1g", "%.0g"):
        print(fmt, fmt % (99994 / divi))

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

# make sure trailing zeroes are added properly
for prec in range(8):
    print(("%%.%df" % prec) % 1e19)

# 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)

# Check a problem with malformed "e" format numbers on the edge of 1.0e-X.
for r in range(38):
    s = "%.12e" % float("1e-" + str(r))
    # It may format as 1e-r, or 9.999...e-(r+1), both are OK.
    # But formatting as 0.999...e-r is NOT ok.
    if s[0] == "0":
        print("FAIL:", s)