c语言程序设计课件ppt（英文）c program language 之3 inpu and output

Chapter TInpu and OutputContents1Data output2Data input3Examples4Control flow-sequenceControl flow-sequenceABNotes in sequence structure Declaration statements first ,then execution statements; Execution statements review: Assignment statement Compond statement expression statementInput /output function call statementInitialization : assign value while declaration;main( ) int a;a=5;main( ) int a=5;Data outputv Character input and outputv Formatted input and outputYour programs will need to include the standard I/O header file so do: #include Input and output are not part of the C There are a set of functions that provide input and output in standard library.NoteCharacter outputputchar(char variable）Formatoutputs a single character to screen.Role Only single characterResult #includeData output#includemain( ) char c=a;putchar( c);Examplemain( ) char c1， c2,c3;c1=a;c2=b;c3=c;putchar(c1);putchar(c2);putchar(c3); How many characters will be displayed ?How about their arrangement? Data outputData outputResultFormatRole NoteFormatted outputprintf ( control string, argument list )Output the variables value in the given format on screenNo argument, only print out control string.printf(“Hello!”);Arguments including constants, variables, mathematical expressionsData outputtype conversion specifier. Control string:Format Output% d output int value in decimal form % o output int value in octal form % x output int value in hexadecimal form% ld: output long int value in decimal form% u output unsign int value in decimal form% f output float value in decimal form% e output float value in exponent formData outputFormat Output% c Output one character% s Output a string% g Output the shorter one between %e and %f% md the output width is m ， flush right% -md the output width is m ， flush left% m.nf the output width is m ， decimal part is n ， flush right% -m.nf the output width is m ， decimal part is n ， flush lefttype conversion specifier printf uses its first argument to decide how many arguments follow and what their type is . It will get confused ,and you will get wrong answers, if there are not enough arguments of if they are the wrong type. Data outputprintf(“%d,%d n”,a,b); if： a=5,b=8a=5,b= 8 printf(“a=%d,b=%dn”,a,b); 5, 8 printf(“%5d%5dn”,a,b); 5 8printf(“Turbo C”); Turbo Cprintf(“%s ”, “Turbo C”); Turbo Cmain() int a=16; char e =A; unsigned b; long c; float d;b=65535; c=123456; d=123.45;printf(“a=%d,%4d,%- 6d,c=%dn”,a,a,a,c);printf(“%o,%x,%u,%dn”,b,b,b,b );printf(“%f,%e,%13.3e,%gn”,d,d,d,d);printf(“%c,%s,%7.3sn”,e,” China”,”Beijing”);a=16, 16,16 , c= - 7616177777, ffff ,65535 , -1123.450000,1.234500e+002, 1.235e+002,123.45A, China, BeiData outputData outputFormat 2 Format 3Format 1 Character input functions and formatted input function1、 character input Inputs a single character from keyboard.Input ，no display ，no Entergetch( )Input and display ,no Entergetche( )After inputing ，one should press Enter keygetchar( )main() int a=3,b=5;printf(“%d,%d,%dn”,a,b, a+b);getch();Data input main( ) char c;c=getchar( );putchar(c); Output the character what you input 2 formatted inputscanf(control string， arguments list）Format:scanf reads characters from the standard input, interprets them according to the specification in format and stores the results through the remaining arguments.Result: the arguments list must be address , indicate where the corresponding converted input should be stored.Note:int a,b;scanf(“%d,%d”, Data input Discussion Format control string similar to printf The arguments are ADDRESS of variables If the inputs dont match, the type conversion specifier, the scanf will stop reading the inputs,return an errorscanf will terminate entry of string when it reads the first space or new line.If the input string length is larger than 3,The first 3 chars are assigned to address others are K;scanf(“%3d”,input： 123456789 K is 123main() int a; float b,c;scanf(“%2d%3f%4f”,printf(“a=%d,b=%f,c=%fn”,a,b,c);input： 12345678987654321output?a=12,b=345.000000,c=6789.00000012 345 6789Data input If additional chars are inserted in control string, they must appear in the input a,b;scanf(“%d%d”, scanf(“%d ,%d”, 3 , 5 scanf(“a =%d,b=%d”, Input： a=3,b=5 char c1,c2,c3; scanf(“%c%c%c ”, A B