C/C++, KDEVELOP |
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BasicsProgram FlowFunctionsClasses and ObjectsX WindowKDevelop----------------- © Alfred Nussbaumer Updated: 09 December 2021 ----------------- |
LoopsThe For-StatementThe for-statement is one of the most used statements in C++ (and in other languages ;-)). It is used, when a loop has a well known number of repetitions. The general form is: for (expression1; condition; expression2) { statement1; statement2; ... } Example: #include <iostream.h> #define NUMBER 10 float values[NUMBER]; int input_numbers(); float output_average(); int main() { input_numbers(); cout << endl << "Average: " << output_average() << endl; } int input_numbers() { for (int i=0; i<NUMBER; i++) { cout << "(" << i << ") number: "; cin >> values[i]; } return 0; } float output_average() { float sum = 0; for (int i=0; i<NUMBER; i++) { sum += values[i]; cout << "."; } return sum/NUMBER; }toc The While-StatementThe last example enables you to put in 10 numbers - exactly 10 numbers. When the number of inputs is unknown you would prefer to use a while-statement... The general form ist: while (condition) { statement1; statement2; ... } The following example shows how to calculate the average of input numbers. The "while"-loop terminates when the input is 0 or when the array is full (see "break"-statement). #include <iostream.h> #define NUMBER 100 float values[NUMBER]; int input_numbers(); float output_average(); int main() { input_numbers(); cout << endl << "Average: " << output_average() << endl; } int input_numbers() { int i=0; int n=1; cout << "0 ... Exit" << endl; while (n!=0) { cout << "(" << i << ") value: "; cin >> n; values[i]=n; i++; if (i > NUMBER) break; } return 0; } float output_average() { float sum = 0; int i=0; while (values[i]!=0) { sum+=values[i]; cout << "."; i++; } return sum/i; } Here is a sample run: 0 ... Exit (0) value: 3 (1) value: 3 (2) value: 2 (3) value: 1 (4) value: 0 .... Average: 2.25toc The Do-While-StatementThe statements will be executed while the condition is true - the condition evaluates after all statements have been executed (compare that with the "while"-statement). The general form is: do { statement1; statement2; ... } while (condition);toc Break and ContinueThe "break"-statement is used to interrupt a "for"-, "while"- or "do-while"-loop (for example that would be necessary if an error inside the loop has been detected). The general form is: if (condition) break; The "continue"-statement forces the loop to start the next iteration. if (condition) continue;toc |