Basic types
Every type have a default value:
| Type | Representation | Initial value | Storage | Max. value |
|---|
| byte | singed integer | 0 | 8 bits | 127 |
| short | singed integer | 0 | 16 bits | 32767 |
| int | singed integer | 0 | 32 bits | 2147483647 |
| long | singed integer | 0 | 64 bits | over 10^18 |
| float | floating point | 0.0 | 32 bits | over 10^38 |
| double | floating point | 0.0 | 64 bits | over 10^308 |
| boolean | true or false | false | 1 bit | |
| char | UNICODE (not ASCII) | u0000 | 16 bits | uFFFF |
Difference between i++ and ++i
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2
| b = 1;
a = b++; // a = 1; b = 2
|
1
2
| b = 1;
a = ++b; // a = 2; b = 2
|
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2
3
| int a = 1;
int res = a++ + a;
// res = 3 ; a = 2.
|
1
2
3
| int a = 1;
int res = a + a++;
// res = 2; a = 2.
|
1
2
3
| int a = 1;
int res = ++a + a;
// res = 4; a = 2.
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1
2
3
| int a = 1;
int res = a + ++a;
// res = 3; a = 2.
|
For loop
for(int i=0; i < n ; i++)
Break or continue the outer loop
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| class TestContinueLabel{
public static void main (String args[]){
outer:
for(int i = 1; i < 5; i++){
System.out.println("Begin outer for i="+i);inner:
for (int j = 1; j < 5; j++){
if (j == i) continue outer;
System.out.println("inner: i=" + i + " j="+j );
}
System.out.println("End outer for i="+i);
}
System.out.println("Finished.");
}
}
|
Result:
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11
| Begin outer for i=1
Begin outer for i=2
inner: i=2 j=1
Begin outer for i=3
inner: i=3 j=1
inner: i=3 j=2
Begin outer for i=4
inner: i=4 j=1
inner: i=4 j=2
inner: i=4 j=3
Finished.
|
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15
| class TestBreakLabel{
public static void main (String args[]){
outer:
for(int i = 1; i < 5; i++){
System.out.println("Begin outer for i="+i);
inner:
for (int j = 1; j < 5; j++){
if (j == i) break outer;
System.out.println("inner: i=" + i + " j="+j );
}
System.out.println("End outer for i="+i);
}
System.out.println("Finished.");
}
}
|
Result:
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2
| Begin outer for i=1
Finished.
|
C++ only use goto to achieve this feature
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| void TestContinueLabel(){
for (int i = 1; i < 5; ++i)
{
cout << "Begin outer for i=" << i << endl;
for (int j = 1; j < 5; ++j)
{
if(i == j)
goto ContinueTry;
cout << "inner: i=" << i << " j=" << j << endl;
}
cout << "End outer for i=" << i << endl;
ContinueTry:;
}
cout << "Finished." << endl;
}
|
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| void TestBreakLabel(){
for (int i = 1; i < 5; ++i)
{
cout << "Begin outer for i=" << i << endl;
for (int j = 1; j < 5; ++j)
{
if(i == j)
goto BreakTry;
cout << "inner: i=" << i << " j=" << j << endl;
}
cout << "End outer for i=" << i << endl;
}
BreakTry:
cout << "Finished." << endl;
}
|