<cstring>
strcpy(destination, source) incl. sentinel char |
strcat(destination, source) |
strcmp(str1, str2); if = 0 then equal, if >0 then str1 is greater else str1 is smaller |
strlen(char* str) returns int; not include sentinel |
strncpy(dest,src, number of characters) |
strncat(d,s,n); strncmp(d,s,n) |
strchr(char str, char) returns a pointer (char) to the first occurence of char in str else returns null |
strstr(str1, str2) returns pointer to first occurence of str2 in str1 (e.g. ptr = strstr(str1, "hello") |
<cmath>
abs(int) returns the absolute of the int |
pow(base, exponent) returns the power |
sqrt(number) returns the square root |
ceil(number) rounds up; floor(number) rounds down |
<cstdlib>
atoi(str) converts str to int; atof(str) converts str to double; use with c strings (char *) |
exit(1) |
x = rand() % number; srand(time(NULL) requires <time.h> |
itoa(value, array, base); value = str to be converted; array = c string array; base = 10, 2, 16, etc. |
Pointers
- Pointer is the memory address of a variable (i.e. int * num_ptr)
- Use typedef to declare variable type (i.e. typedef int* num_ptr -> num_ptr X;)
- Create dynamic var: ptr = new type; delete dynamic var: delete ptr
- Deleting dynamic var does not delete the ptr just what is stored inside it
- Make sure to assign null to ptr after delete so it is not dangling
ptr_a = new (nothrow) int;
if (ptr_a == NULL) {
cout << "sorry";
exit(1); } <- ptr set to null if allocation fails
- array identifiers are pointers
int hours[5];
int* ptr;
ptr = hours; <- both point to first index
- hours[1] is equivalent to *(hours+1)
- char phrase[] is equivalent to char* phrase
int* number_ptr;
number_ptr = new int[10] <- dynamic array
delete [] number_ptr; |
Strings
- Sentinel character is '\0' and marks the end of string
- char phrase[5] = {'A', 'B'} or char phrase[] = "Hello"
- Using >> to input strings is limited because it ends at white space
- cin.getline(string_name, 80) is often used instead |
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<algorithm>
swap(var1, var2) swaps the 2 variables; also works arrays/vector |
min(val1,val2), max(val1,val2); |
find(begin, end, val); if no found return end |
replace(begin,end,oldval,newval) |
sort(begin, end) |
<cctype>
tolower(char) converts to lowercase; toupper(char) converts to upper case |
isalpha(char) returns true if char is alphabetic (0 = false) |
isalnum(char) returns true if char is decimal, upper/lower |
isblank(char), isspace(char) return true if char is either ' ' or \n |
isupper(char), islower(char), isdigit(char) are all boolean |
ispunct(char) returns true if char is punctuation |
letter to number / number to letter
int -> char
int number = 40;
char letter = number;
char -> int
char letter = 'c';
int number = letter;
notes:
ASCII for 0 = 48
ASCII for space = 32
ASCII for A = 65
ASCII for a = 97 |
Streams
- connect: stream.open("name"); <- connects to the beginning of the file
- disconnect: stream.close();
stream.open("name")
if (stream.fail()) {
sorry + exit }
- in_stream.get(ch) -> assigns ch the next char in the file and repositions file
- out_stream.put(ch) -> puts ch in next position in file
- in_stream.putback(ch) -> puts back in the file but does not alter file
- char = in_stream.peek() assigns char the next char in file but does not move it forward
in_stream.get(ch)
while (! in_stream.eof()) {
cout << ch;
out_stream.put(ch);
in_stream.get(ch) }
- streams must be reference & arguments in functions only |
GDB
- 'gdb' to start gdb
- Start with 'run' or 'r'
- Set breakpoint with 'break'
- Print variable_name, &variable_address
- 'Watch' variable_name
- 'C' for continue
- Execute next line using 'step' or 's'
- 'Next' or 'n'
- Pressing enter repeats last command
- 'q' to quit
- 'finish' to stop execution of current function |
Loops
- Do { ... } While (bool)
switch (selector) {
case label1:
statement;
break;
default:
statment;
break; } |
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<array>
array_name.begin() / array_name.end = first and last elements in the array; also .front/.back |
array_name.size() = number of elements in the array vs. sizeof(expression/type) = bytes |
array_name.max_size() returns max number of elements allowed in array |
array_name.empty() returns true if array size is 0 meaning no elements |
array_name.at(int) = array at position int like array_name[int] |
<string>
getline(input_stream, str, optional_limit) |
begin(array); end(array); .begin/.end |
Makefiles
exe: main.o exe.o
(tab) g++ -g main.o exe.o -o exe
main.o: main.cpp exe.h
(tab) g++ -Wall -c main.cpp
exe.o: exe.cpp exe.h
(tab) g++ -Wall -c exe.cpp
Input/Output with >> & <<
- out_stream << 34 << ' ' would result in '3', '4', ' ' as characters in output file
- doing input_stream >> number would take all characters together until reaching a blank space
- >> skips over blank space no matter the data type
Arrays
- When declaring a function that passes an array use []
- When passing actual array to function no need to use []
- Array parameters are essentially reference parameters but not need to use &
- Pass the size of the array in the function as well
- Add const before array in function if you don't want it to change the array e.g. const int array_name[]
- 2D arrays -> int array_name[row][column]
- function(array[][column]) |
Header file (function declarations)
#ifndef HEADERNAME_H
#define HEADERNAME_H
#include directives
Using directives
statements
#endif
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Another Makefile
OBJ = main.o tube.o helper.o
EXE = tube
CXX = g++
CXXFLAGS = -Wall -g
$(EXE): $(OBJ)
$(CXX) $(OBJ) -o $@
%.o: %.cpp
$(CXX) $(CXXFLAGS) -c $<
main.o: tube.h
tube.o: tube.h helper.h
helper.o: helper.h
clean:
rm -f $(OBJ) $(EXE)
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