COMP26120: Algorithms and Imperative Programming Lecture C1: - - PowerPoint PPT Presentation

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COMP26120: Algorithms and Imperative Programming Lecture C1: - - PowerPoint PPT Presentation

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COMP26120: Algorithms and Imperative Programming Lecture C1: Introduction to C Pete Jinks School of Computer Science, University of Manchester Autumn 2011 COMP26120 Lecture C1 1/25 Review Course-unit Contents: Algorithms C

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COMP26120: Algorithms and Imperative Programming

Lecture C1: Introduction to C Pete Jinks

School of Computer Science, University of Manchester

Autumn 2011

COMP26120 Lecture C1 1/25

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Review

Course-unit Contents: – Algorithms – C programming Course-unit Approach: – Active Learning – Reading

COMP26120 Lecture C1 2/25

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Review

Course-unit Contents: – Algorithms – C programming Course-unit Approach: – Active Learning – Reading

COMP26120 Lecture C1 2/25

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Lecture Outline

C Resources Comparing Java and C Input/Output

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Lecture C1: You are here

C Resources Comparing Java and C Input/Output

COMP26120 Lecture C1 C 4/25

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Motivation

New Programming Language Paradigm Concepts Useful for certain applications – uncluttered view of hardware (“high-level assembly-code”) – performance CV

COMP26120 Lecture C1 C 5/25

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Motivation

New Programming Language Paradigm Concepts Useful for certain applications – uncluttered view of hardware (“high-level assembly-code”) – performance CV

COMP26120 Lecture C1 C 5/25

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Motivation

New Programming Language Paradigm Concepts Useful for certain applications – uncluttered view of hardware (“high-level assembly-code”) – performance CV

COMP26120 Lecture C1 C 5/25

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A little history

Originally from late 60’s - published 1972 1989/1990 ISO standard (C89, C90) 1999/2000 ISO standard (C99) 201? (C1X)

COMP26120 Lecture C1 C 6/25

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Lecture C1: You are here

C Resources Comparing Java and C Input/Output

COMP26120 Lecture C1 Resources 7/25

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Online Resources

Starting points: Syllabus: http://www.cs.manchester.ac.uk/undergraduate/ programmes/courseunits/syllabus.php?code=COMP26120 Course-unit: http://www.cs.manchester.ac.uk/ugt/COMP26120/ QandA: http://qanda.cs.man.ac.uk/questions/3842/ resources-for-learning-c (tag: comp261-algorithms+c) Point to: – Online C course in Moodle – Online “Standard C” book (Plauger & Brodie) – etc.

COMP26120 Lecture C1 Resources 8/25

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Online Resources

Starting points: Syllabus: http://www.cs.manchester.ac.uk/undergraduate/ programmes/courseunits/syllabus.php?code=COMP26120 Course-unit: http://www.cs.manchester.ac.uk/ugt/COMP26120/ QandA: http://qanda.cs.man.ac.uk/questions/3842/ resources-for-learning-c (tag: comp261-algorithms+c) Point to: – Online C course in Moodle – Online “Standard C” book (Plauger & Brodie) – etc.

COMP26120 Lecture C1 Resources 8/25

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More Resources

man pages etc. Book list on syllabus:

  • The C Programming Language (Kernighan & Ritchie)
  • C: A Reference Manual (Harbison & Steele)
  • Expert C Programming (van der Linden)

COMP26120 Lecture C1 Resources 9/25

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Online C course

http://moodle.cs.man.ac.uk/file.php/28/coursedata/c cbt/ frontpage.html Navigation: begin return map index Themes : – Java to C – Information Representation – Control Flow – Program Structuring – Input & Output Colour-coding: green, yellow, orange, red Dependencies/Routes (arrows) e.g. use for C labs

COMP26120 Lecture C1 Resources 10/25

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Online C course

http://moodle.cs.man.ac.uk/file.php/28/coursedata/c cbt/ frontpage.html Navigation: begin return map index Themes : – Java to C – Information Representation – Control Flow – Program Structuring – Input & Output Colour-coding: green, yellow, orange, red Dependencies/Routes (arrows) e.g. use for C labs

COMP26120 Lecture C1 Resources 10/25

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Online C course

http://moodle.cs.man.ac.uk/file.php/28/coursedata/c cbt/ frontpage.html Navigation: begin return map index Themes : – Java to C – Information Representation – Control Flow – Program Structuring – Input & Output Colour-coding: green, yellow, orange, red Dependencies/Routes (arrows) e.g. use for C labs

COMP26120 Lecture C1 Resources 10/25

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Online C course

http://moodle.cs.man.ac.uk/file.php/28/coursedata/c cbt/ frontpage.html Navigation: begin return map index Themes : – Java to C – Information Representation – Control Flow – Program Structuring – Input & Output Colour-coding: green, yellow, orange, red Dependencies/Routes (arrows) e.g. use for C labs

COMP26120 Lecture C1 Resources 10/25

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Online C course

http://moodle.cs.man.ac.uk/file.php/28/coursedata/c cbt/ frontpage.html Navigation: begin return map index Themes : – Java to C – Information Representation – Control Flow – Program Structuring – Input & Output Colour-coding: green, yellow, orange, red Dependencies/Routes (arrows) e.g. use for C labs

COMP26120 Lecture C1 Resources 10/25

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Lecture C1: You are here

C Resources Comparing Java and C Input/Output

COMP26120 Lecture C1 Comparing Java and C 11/25

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Assumptions

You have successfully completed 1st-year Java (or equivalent): – you know how to design non-trivial programmes – you know how to encode your designs using Java You are going to learn C based on this C and Java have a lot of similarities, and a lot of differences Look at programming concepts, saying for each whether C is – similar to Java (but ...) – different from Java (as follows ...)

COMP26120 Lecture C1 Comparing Java and C 12/25

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Assumptions

You have successfully completed 1st-year Java (or equivalent): – you know how to design non-trivial programmes – you know how to encode your designs using Java You are going to learn C based on this C and Java have a lot of similarities, and a lot of differences Look at programming concepts, saying for each whether C is – similar to Java (but ...) – different from Java (as follows ...)

COMP26120 Lecture C1 Comparing Java and C 12/25

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SalaryAnalysis

You should have seen the Java version (or something very similar) last year. Compare the Java and C versions Check center character: “ ” = same in both “|” = in both, but different “<” = only in .java “>” = only in .c Start making a list of similarities and differences. Please work with your neighbour(s).

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Lecture C1: You are here

C Resources Comparing Java and C Input/Output

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Streams

Moodle theme: Input and Output man stdio etc. Built-in: System.in → stdin System.out → stdout System.err → stderr e.g. System.out.print(...) → fprintf(stdout, ...)

COMP26120 Lecture C1 Input/Output 15/25

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Streams

Moodle theme: Input and Output man stdio etc. Built-in: System.in → stdin System.out → stdout System.err → stderr e.g. System.out.print(...) → fprintf(stdout, ...)

COMP26120 Lecture C1 Input/Output 15/25

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Streams

Moodle theme: Input and Output man stdio etc. Built-in: System.in → stdin System.out → stdout System.err → stderr e.g. System.out.print(...) → fprintf(stdout, ...)

COMP26120 Lecture C1 Input/Output 15/25

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Creating your own Streams

Moodle: Input and Output Streams, Manipulating Streams import java.util.Scanner; import java.io.File; → #include <stdio.h> #include <stdlib.h> Scanner sScan = new Scanner(new File(filen)); → FILE *stream= fopen(filen, "r"); if (!stream) { fprintf(stderr, "can’t open %s\n", filen); exit(-1); } ? → fclose(stream);

COMP26120 Lecture C1 Input/Output 16/25

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Creating your own Streams

Moodle: Input and Output Streams, Manipulating Streams import java.util.Scanner; import java.io.File; → #include <stdio.h> #include <stdlib.h> Scanner sScan = new Scanner(new File(filen)); → FILE *stream= fopen(filen, "r"); if (!stream) { fprintf(stderr, "can’t open %s\n", filen); exit(-1); } ? → fclose(stream);

COMP26120 Lecture C1 Input/Output 16/25

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Creating your own Streams

Moodle: Input and Output Streams, Manipulating Streams import java.util.Scanner; import java.io.File; → #include <stdio.h> #include <stdlib.h> Scanner sScan = new Scanner(new File(filen)); → FILE *stream= fopen(filen, "r"); if (!stream) { fprintf(stderr, "can’t open %s\n", filen); exit(-1); } ? → fclose(stream);

COMP26120 Lecture C1 Input/Output 16/25

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Writing characters

Moodle: Character Manipulation, Revisited putchar(ch) – character fputc(stream, ch) putchar(ch) is fputc(stdout,ch) printf(...) – formatted fprintf(stream, ...) sprintf(string, ...) printf(...) is fprintf(stdout, ...)

COMP26120 Lecture C1 Input/Output 17/25

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Writing characters

Moodle: Character Manipulation, Revisited putchar(ch) – character fputc(stream, ch) putchar(ch) is fputc(stdout,ch) printf(...) – formatted fprintf(stream, ...) sprintf(string, ...) printf(...) is fprintf(stdout, ...)

COMP26120 Lecture C1 Input/Output 17/25

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printf

Moodle: (Reading and) Writing System.out.print (String.format(...)); → printf (...); ("%2d earns %5d, which is %5d %s", i, j, k, s) println("...", ...) → printf("...\n", ...) System.out.println("mean is:\t" + mSal); System.out.println("rounds to:\t" + mSalR); → printf("mean is:\t%f\n" "rounds to:\t%d\n", mSal, mSalR);

COMP26120 Lecture C1 Input/Output 18/25

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printf

Moodle: (Reading and) Writing System.out.print (String.format(...)); → printf (...); ("%2d earns %5d, which is %5d %s", i, j, k, s) println("...", ...) → printf("...\n", ...) System.out.println("mean is:\t" + mSal); System.out.println("rounds to:\t" + mSalR); → printf("mean is:\t%f\n" "rounds to:\t%d\n", mSal, mSalR);

COMP26120 Lecture C1 Input/Output 18/25

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printf

Moodle: (Reading and) Writing System.out.print (String.format(...)); → printf (...); ("%2d earns %5d, which is %5d %s", i, j, k, s) println("...", ...) → printf("...\n", ...) System.out.println("mean is:\t" + mSal); System.out.println("rounds to:\t" + mSalR); → printf("mean is:\t%f\n" "rounds to:\t%d\n", mSal, mSalR);

COMP26120 Lecture C1 Input/Output 18/25

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printf

Moodle: (Reading and) Writing System.out.print (String.format(...)); → printf (...); ("%2d earns %5d, which is %5d %s", i, j, k, s) println("...", ...) → printf("...\n", ...) System.out.println("mean is:\t" + mSal); System.out.println("rounds to:\t" + mSalR); → printf("mean is:\t%f\n" "rounds to:\t%d\n", mSal, mSalR);

COMP26120 Lecture C1 Input/Output 18/25

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Reading characters

Moodle: Reading (and Writing), Revisited while (salariesScanner.hasNextLine()) String data = salariesScanner.nextLine(); → enum {buffer size = 100}; char data[buffer size]; while (fgets(data, buffer size, stream)) int currentsalary = Integer.parseInt(data); → int currentsalary = atoi(data);

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Reading characters

Moodle: Reading (and Writing), Revisited while (salariesScanner.hasNextLine()) String data = salariesScanner.nextLine(); → enum {buffer size = 100}; char data[buffer size]; while (fgets(data, buffer size, stream)) int currentsalary = Integer.parseInt(data); → int currentsalary = atoi(data);

COMP26120 Lecture C1 Input/Output 19/25

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scanf

ch=getchar() – character ch=fgetc(stream) getchar() is fgetc(stdin) scanf(...) – formatted fscanf(stream, ...) sscanf(string, ...) scanf(...) is fscanf(stdin, ...)

COMP26120 Lecture C1 Input/Output 20/25

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scanf

ch=getchar() – character ch=fgetc(stream) getchar() is fgetc(stdin) scanf(...) – formatted fscanf(stream, ...) sscanf(string, ...) scanf(...) is fscanf(stdin, ...)

COMP26120 Lecture C1 Input/Output 20/25

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Reading a line of input

#define __USE_BSD #include <string.h> char * nextline (FILE* stream) { char data [buffer_size]; fgets (data, buffer_size, stream);//test result int len= strlen (data); data[len-1]= ’\0’; //test was ’\n’ char* temp= strdup (data); //test result return temp; }

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Reading fields from an input line

char one[buffer_size], two[buffer_size], three[buffer_size]; sscanf(data, "%s %s %s", one, two, three); Result of sscanf = number of things read or EOF

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Reading fields from an input line

char one[buffer_size], two[buffer_size], three[buffer_size]; sscanf(data, "%s %s %s", one, two, three); Result of sscanf = number of things read or EOF

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Lecture Review

C Resources

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