📄 bc.1
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1728 V1080(less)S1260(of)S1373(the)S1525(value)S1772(of)S10 B1885(ibase)S10 R2103(.)S2157(\(i.e.)S2343(A)S2445(=)S2531(10.\))S2744(For)S(multi-digit)430 2913 A3372(numbers,)S10 B3772(bc)S10 R3902(changes)S4254(all)S(input)206 4383 A4617(digits)S4868(greater)S5177(or)S1848 V1080(equal)S1340(to)S1460(ibase)S1709(to)S1829(the)S1995(value)S2256(of)S10 B2383(ibase)S10 R2601(-1.)S2778(This)S3000(makes)S3300(the)S3466(number)S10 B(FFF)186 3816 A10 R4045(always)S4368(be)S4506(the)S4672(largest)S4984(3)S5077(digit)S1968 V1080(number)S1412(of)S1521(the)S(input)206 1669 A1900(base.)S2136 V1080(Full)S1287(expressions)S1801(are)S1971(similar)S2297(to)S2421(many)S2690(other)S2943(high)S3167(level)S(languages.)427 3409 A3907(Since)S4177(there)S4425(is)S4538(only)S4762(one)S4953(kind)S5177(of)S2256 V1080(number,)S1439(there)S1668(are)S1819(no)S1946(rules)S2169(for)S2314(mixing)S2625(types.)S2914(Instead,)S3257(there)S3486(are)S3637(rules)S3860(on)S3987(the)S4137(scale)S4365(of)S4475(expressions.)S5020(Every)S2376 V1080(expression)S1535(has)S1695(a)S1766(scale.)S2044(This)S2249(is)S2342(derived)S2670(from)S2892(the)S3041(scale)S3269(of)S3379(original)S3718(numbers,)S4115(the)S4264(operation)S4670(performed)S5116(and)S2496 V1080(in)S1186(many)S1437(cases,)S1703(the)S1854(value)S2100(of)S2212(the)S2363(variable)S10 B2716(scale)S10 R2923(.)S2976(Legal)S3234(values)S3519(of)S3631(the)S3782(variable)S10 B4135(scale)S10 R4370(are)S4522(0)S4599(to)S4704(the)S4854(maximum)S2616 V1080(number)S1412(representable)S1975(by)S2100(a)S2170(C)S2262(integer.)S2784 V1080(In)S1203(the)S1365(following)S1795(descriptions)S2320(of)S2443(legal)S2678(expressions,)S3211("expr")S3512(refers)S3783(to)S3901(a)S3986(complete)S4395(expression)S4865(and)S5050("var")S2904 V1080(refers)S1336(to)S1439(a)S1509(simple)S1802(or)S1911(an)S2031(array)S2264(variable.)S2664(A)S2762(simple)S3055(variable)S3405(is)S3497(just)S3667(a)S3024 V10 I1440(name)S3144 V10 R1080(and)S1250(an)S1370(array)S1603(variable)S1953(is)S2045(speci\256ed)S2428(as)S3264 V10 I1440(name)S10 R1658([)S10 I1692(expr)S10 R1871(])S3384 V1080(Unless)S1379(speci\256cally)S1863(mentioned)S2312(the)S2460(scale)S2687(of)S2796(the)S2944(result)S3193(is)S3285(the)S3433(maximum)S3865(scale)S4092(of)S4201(the)S4349(expressions)S(involved.)376 4843 A3552 V1080(-)S1139(expr)S1440(The)S1622(result)S1871(is)S1963(the)S2111(negation)S2482(of)S2591(the)S2739(expression.)S3720 V1080(++)S1219(var)S1440(The)S1622(variable)S1972(is)S2064(incremented)S2587(by)S2712(one)S2882(and)S3052(the)S3200(new)S3393(value)S3636(is)S3728(the)S3876(result)S4125(of)S4234(the)S4382(expression.)S3888 V1080(--)S1173(var)S1440(The)S1622(variable)S1972(is)S2064(decremented)S2604(by)S2729(one)S2899(and)S3069(the)S3217(new)S3410(value)S3653(is)S3745(the)S3893(result)S4142(of)S4251(the)S4399(expression.)S4056 V1080(var)S1234(++)S1471(The)S1659(result)S1914(of)S2029(the)S2183(expression)S2644(is)S2742(the)S2896(value)S3145(of)S3260(the)S3414(variable)S3770(and)S3947(then)S4152(the)S4307(variable)S4664(is)S4763(incremented)S4176 V1440(by)S1565(one.)S4344 V1080(var)S1234(--)S1440(The)S1629(result)S1885(of)S2001(the)S2156(expression)S2618(is)S2717(the)S2872(value)S3122(of)S3238(the)S3393(variable)S3750(and)S3927(then)S4132(the)S4288(variable)S4646(is)S4746(decremented)S4464 V1440(by)S1565(one.)S4632 V1080(expr)S1284(+)S1366(expr)S4752 V1440(The)S1622(result)S1871(of)S1980(the)S2128(expression)S2583(is)S2675(the)S2823(sum)S3015(of)S3124(the)S3272(two)S3448(expressions.)S4920 V1080(expr)S1284(-)S1343(expr)S5040 V1440(The)S1622(result)S1871(of)S1980(the)S2128(expression)S2583(is)S2675(the)S2823(difference)S3258(of)S3367(the)S3515(two)S3691(expressions.)S5208 V1080(expr)S1284(*)S1359(expr)S5328 V1440(The)S1622(result)S1871(of)S1980(the)S2128(expression)S2583(is)S2675(the)S(product)307 2823 A3155(of)S3264(the)S3412(two)S3588(expressions.)S5496 V1080(expr)S1284(/)S1337(expr)S5616 V1440(The)S1629(result)S1885(of)S2001(the)S2156(expression)S2618(is)S2717(the)S(quotient)329 2872 A3233(of)S3349(the)S3504(two)S3687(expressions.)S4239(The)S4429(scale)S4664(of)S4781(the)S4937(result)S5194(is)S5736 V1440(the)S1588(value)S1831(of)S1940(the)S2088(variable)S10 B2438(scale)S10 R2645(.)S5904 V1080(expr)S1284(%)S1393(expr)S6024 V1440(The)S1630(result)S1887(of)S2004(the)S2160(expression)S2623(is)S2723(the)S2879("remainder")S3403(and)S3582(it)S3672(is)S3773(computed)S4203(in)S4315(the)S4472(following)S4897(way.)S5149(To)S6144 V1440(compute)S1814(a%b,)S2046(\256rst)S2231(a/b)S2382(is)S2477(computed)S2901(to)S10 B3006(scale)S10 R3240(digits.)S3540(That)S3752(result)S4003(is)S4097(used)S4308(to)S4413(compute)S4786(a-\(a/b\)*b)S5183(to)S6264 V1440(the)S1605(scale)S1849(of)S1975(the)S2140(maximum)S2589(of)S10 B2715(scale)S10 R2922(+scale\(b\))S3341(and)S3528(scale\(a\).)S3935(If)S10 B4045(scale)S10 R4294(is)S4403(set)S4557(to)S4678(zero)S4895(and)S5083(both)S6384 V1440(expressions)S1934(are)S2083(integers)S2427(this)S2597(expression)S3052(is)S3144(the)S3292(integer)S3597(remainder)S4031(function.)S6552 V1080(expr)S1284(\303)S1343(expr)S6672 V1440(The)S1629(result)S1885(of)S2001(the)S2156(expression)S2618(is)S2717(the)S2872(value)S3122(of)S3238(the)S3394(\256rst)S3584(raised)S3858(to)S3969(the)S(second.)304 4125 A4462(The)S(second)279 4652 A4964(expres-)S6792 V1440(sion)S1633(must)S1854(be)S1975(an)S2096(integer.)S(\(If)102 2452 A2580(the)S(second)279 2728 A3032(expression)S3487(is)S3579(not)S3732(an)S3852(integer,)S4182(a)S4252(warning)S4607(is)S4699(generated)S5116(and)S6912 V1440(the)S1604(expression)S2075(is)S2183(truncated)S2599(to)S2718(get)S2882(an)S3018(integer)S3339(value.\))S3682(The)S3880(scale)S4123(of)S4248(the)S4412(result)S4677(is)S10 B4785(scale)S10 R5034(if)S5138(the)S7032 V(exponent)368 1440 A1838(is)S1935(negative.)S2356(If)S2454(the)S(exponent)368 2607 A3005(is)S(positive)318 3102 A3450(the)S3603(scale)S3835(of)S3949(the)S4102(result)S4356(is)S4453(the)S4606(minimum)S5025(of)S5138(the)S7152 V1440(scale)S1668(of)S1778(the)S1928(\256rst)S2112(expression)S2569(times)S2814(the)S2964(value)S3209(of)S3320(the)S(exponent)368 3470 A3865(and)S4037(the)S4187(maximum)S4621(of)S10 B4732(scale)S10 R4966(and)S5138(the)S7272 V1440(scale)S1688(of)S1818(the)S1986(\256rst)S2188(expression.)S2713(\(e.g.)S2937(scale\(a\303b\))S3381(=)S3483(min\(scale\(a\)*b,)S4158(max\()S10 B4410(scale,)S10 R(scale\(a\)\)\).\))442 4687 A5199(It)S7392 V(should)267 1440 A1732(be)S1852(noted)S2100(that)S2276(expr\3030)S(will)157 2564 A2746(always)S3051(return)S3317(the)S3465(value)S3708(of)S3817(1.)S7903 V720(September)S1176(13,)S(1996)200 1326 A2936(\()S2978(.)S3011(\))S4990(Page)S5211(2)S8143 VEP%%Page: 3 3BP/slant 0 def/height 0 def480 V10 R720(bc)S823(\()S865(1)S923(\))S2696(Eighth)S(Edition)296 2989 A5024(bc)S5127(\()S5169(1)S5227(\))S960 V1080(\()S1139(expr)S1343(\))S1440(This)S1644(alters)S1888(the)S2036(standard)S(precedence)454 2402 A2881(to)S2984(force)S3217(the)S3365(evaluation)S3809(of)S3918(the)S4066(expression.)S1128 V1080(var)S1234(=)S1316(expr)S1248 V1440(The)S1622(variable)S1972(is)S2064(assigned)S2435(the)S2583(value)S2826(of)S2935(the)S3083(expression.)S1416 V1080(var)S1234(<op>=)S1530(expr)S1536 V1440(This)S1648(is)S1744(equivalent)S2192(to)S2299("var)S2498(=)S2584(var)S2742(<op>)S2985(expr")S3234(with)S3442(the)S3595(exception)S4016(that)S4197(the)S4350("var")S4591(part)S4778(is)S4875(evaluated)S1656 V1440(only)S1643(once.)S1908(This)S2112(can)S2277(make)S2520(a)S2590(difference)S3025(if)S3112("var")S3348(is)S3440(an)S3560(array.)S1824 V1105(Relational)S1548(expressions)S2046(are)S2199(a)S2273(special)S2582(kind)S2790(of)S2904(expression)S3364(that)S3545(always)S3855(evaluate)S4221(to)S4329(0)S4409(or)S4523(1,)S4628(0)S4708(if)S4800(the)S4953(relation)S1944 V1080(is)S1173(false)S1390(and)S1561(1)S1637(if)S1725(the)S1874(relation)S2208(is)S2300(true.)S2532(These)S2798(may)S2996(appear)S3290(in)S3393(any)S3563(legal)S3784(expression.)S4289(\(POSIX)S4640(bc)S4760(requires)S5110(that)S2064 V1080(relational)S1486(expressions)S1980(are)S2129(used)S2338(only)S2541(in)S2644(if,)S2756(while,)S3030(and)S3200(for)S3343(statements)S3793(and)S3963(that)S4140(only)S4344(one)S4515(relational)S4922(test)S5088(may)S2184 V1080(be)S(done)195 1200 A1420(in)S1523(them.\))S1833(The)S2015(relational)S2421(operators)S2821(are)S2352 V1080(expr1)S1334(<)S1416(expr2)S2472 V1440(The)S1622(result)S1871(is)S1963(1)S2038(if)S2125(expr1)S2379(is)S2471(strictly)S2776(less)S2952(than)S3150(expr2.)S2640 V1080(expr1)S1334(<=)S1473(expr2)S2760 V1440(The)S1622(result)S1871(is)S1963(1)S2038(if)S2125(expr1)S2379(is)S2471(less)S2647(than)S2845(or)S2954(equal)S3197(to)S3300(expr2.)S2928 V1080(expr1)S1334(>)S1416(expr2)S3048 V1440(The)S1622(result)S1871(is)S1963(1)S2038(if)S2125(expr1)S2379(is)S2471(strictly)S2776(greater)S3082(than)S3280(expr2.)S3216 V1080(expr1)S1334(>=)S1473(expr2)S3336 V1440(The)S1622(result)S1871(is)S1963(1)S2038(if)S2125(expr1)S2379(is)S2471(greater)S2777(than)S2975(or)S3084(equal)S3327(to)S3430(expr2.)S3504 V1080(expr1)S1334(==)S1473(expr2)S3624 V1440(The)S1622(result)S1871(is)S1963(1)S2038(if)S2125(expr1)S2379(is)S2471(equal)S2714(to)S2817(expr2.)S3792 V1080(expr1)S1334(!=)S1450(expr2)S3912 V1440(The)S1622(result)S1871(is)S1963(1)S2038(if)S2125(expr1)S2379(is)S2471(not)S2624(equal)S2867(to)S2970(expr2.)S4080 V1080(Boolean)S1449(operations)S1903(are)S2062(also)S2259(legal.)S2540(\(POSIX)S10 B2901(bc)S10 R3037(does)S3256(NOT)S3499(have)S(boolean)318 3724 A4077(operations\).)S4590(The)S4782(result)S5041(of)S5160(all)S4200 V(boolean)318 1080 A1429(operations)S1879(are)S2034(0)S2115(and)S2290(1)S2370(\(for)S2552(false)S2773(and)S2948(true\))S3169(as)S3283(in)S3391(relational)S3802(expressions.)S4351(The)S(boolean)318 4538 A4886(operators)S4320 V1080(are:)S4488 V1080(!expr)S1440(The)S1622(result)S1871(is)S1963(1)S2038(if)S2125(expr)S2329(is)S2421(0.)S4656 V1080(expr)S1284(&&)S1465(expr)S4776 V1440(The)S1622(result)S1871(is)S1963(1)S2038(if)S2125(both)S2328(expressions)S2822(are)S(non-zero.)383 2971 A4944 V1080(expr)S1284(||)S1349(expr)S5064 V1440(The)S1622(result)S1871(is)S1963(1)S2038(if)S2125(either)S2380(expression)S2835(is)S(non-zero.)383 2927 A5232 V1080(The)S1262(expression)S(precedence)454 1717 A2196(is)S2288(as)S2397(follows:)S2752(\(lowest)S3074(to)S3177(highest\))S5352 V1440(||)S1505(operator,)S1891(left)S2051(associative)S5472 V1440(&&)S1621(operator,)S2007(left)S2167(associative)S5592 V1440(!)S1499(operator,)S(nonassociative)592 1885 A5712 V1440(Relational)S1879(operators,)S2304(left)S2464(associative)S5832 V1440(Assignment)S1945(operator,)S2331(right)S2546(associative)S5952 V1440(+)S1522(and)S1692(-)S1751(operators,)S2176(left)S2336(associative)S6072 V1440(*,)S1540(/)S1593(and)S1763(%)S1872(operators,)S2297(left)S2457(associative)S6192 V1440(\303)S1499(operator,)S1885(right)S2100(associative)S6312 V1440(unary)S1694(-)S1753(operator,)S(nonassociative)592 2139 A6432 V1440(++)S1579(and)S1749(--)S1842(operators,)S(nonassociative)592 2267 A6600 V1080(This)S(precedence)454 1289 A1773(was)S1960(chosen)S2270(so)S2390(that)S2572(POSIX)S2895(compliant)S10 B3328(bc)S10 R3460(programs)S(will)157 3871 A4059(run)S4224(correctly.)S4639(This)S(will)157 4849 A5037(cause)S6720 V1080(the)S1237(use)S1405(of)S1523(the)S1680(relational)S2094(and)S2272(logical)S2579(operators)S2987(to)S3098(have)S3321(some)S(unusual)312 3566 A3911(behavior)S4296(when)S4547(used)S4764(with)S4976(assign-)S6840 V1080(ment)S1306(expressions.)S1850(Consider)S2238(the)S2386(expression:)S6960 V1440(a)S1510(=)S1592(3)S1667(<)S1749(5)S7128 V1080(Most)S1313(C)S1407(programmers)S1971(would)S2249(assume)S2572(this)S2744(would)S3022(assign)S3300(the)S3450(result)S3701(of)S3813("3)S3932(<)S4017(5")S4136(\(the)S4321(value)S4567(1\))S4679(to)S⌨️ 快捷键说明
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