Home » Archimedes archive » Acorn User » AU 1995-05.adf » !C_C » c/printf
c/printf
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| Tape/disk: | Home » Archimedes archive » Acorn User » AU 1995-05.adf » !C_C |
| Filename: | c/printf |
| Read OK: | ✔ |
| File size: | 0971 bytes |
| Load address: | 0000 |
| Exec address: | 0000 |
File contents
/* C for yourself - Acorn User Demonstration C program
by Steve Mumford for Acorn User May 1995
printf, scanf and file access */
#include <stdio.h>
main()
{
int var1 = 15;
int var2 = 34;
float fvar = 14.3782;
FILE *fpointer;
char letter;
printf("printf and scanf - C for Yourself May 1995\n");
printf("------------------------------------------\n\n");
printf("Variable 1 = %d, variable 2 = %d.\n", var1, var2);
printf("Floating point variable = %f\n\n", fvar);
printf("The last variable only has four decimal places, but it was\n");
printf("printed out to six. This can be altered by including other\n");
printf("information along with the conversion specifiers, as follows.\n\n");
printf("Floating point number to 4 decimal places: %.4f\n\n",fvar);
printf("This is how you print a fixed width field:\n");
printf("%7d %7d %7.4f\n", var1, var2, fvar);
printf("%7.4f %7d %7d\n\n", fvar, var2, var1);
printf("You can also change the justification so that the figures are\n");
printf("left justified.\n");
printf("%-7d %-7d %-7.4f\n\n", var1, var2, fvar);
letter = 'B';
printf("Characters can also be printed: %c\n\n",letter);
printf("Please press RETURN to continue.\n");
letter = getchar();
printf("\f"); /* This control code clears the screen */
printf("That last printf cleared the screen by using the code \\f.\n");
printf("If you want to print the \\ character, use \\\\ as the control code.\n\n");
printf("Please enter a new integer for var1:\n");
scanf("%d", &var1);
while (getchar() != '\n');
printf("Now, please enter another integer for var2:\n");
scanf("%d", &var2);
while (getchar() != '\n');
printf("Finally, please enter a floating point number for fvar:\n");
scanf("%f",&fvar);
while (getchar() != '\n');
if ((fpointer = fopen("testfile","w")) == 0) {
printf("File open failed. Please change directory to one which has write access.\n");
return;
}
fprintf(fpointer, "This is some text, and this is variable 1: %d\n", var1);
fprintf(fpointer, "Variable 2: %d\nFloating point variable: %.4f\n", var2, fvar);
if (fclose(fpointer) != 0) {
printf("File close failed. Sorry!\n");
} else {
printf("A text file called \'testfile\' has just been created in the current directory.\n");
printf("Try loading it into Edit...\n");
}
}
00000000 2f 2a 20 43 20 66 6f 72 20 79 6f 75 72 73 65 6c |/* C for yoursel|
00000010 66 20 2d 20 41 63 6f 72 6e 20 55 73 65 72 20 44 |f - Acorn User D|
00000020 65 6d 6f 6e 73 74 72 61 74 69 6f 6e 20 43 20 70 |emonstration C p|
00000030 72 6f 67 72 61 6d 0a 20 20 20 62 79 20 53 74 65 |rogram. by Ste|
00000040 76 65 20 4d 75 6d 66 6f 72 64 20 66 6f 72 20 41 |ve Mumford for A|
00000050 63 6f 72 6e 20 55 73 65 72 20 4d 61 79 20 31 39 |corn User May 19|
00000060 39 35 0a 20 20 20 70 72 69 6e 74 66 2c 20 73 63 |95. printf, sc|
00000070 61 6e 66 20 61 6e 64 20 66 69 6c 65 20 61 63 63 |anf and file acc|
00000080 65 73 73 20 2a 2f 0a 0a 23 69 6e 63 6c 75 64 65 |ess */..#include|
00000090 20 3c 73 74 64 69 6f 2e 68 3e 0a 0a 6d 61 69 6e | <stdio.h>..main|
000000a0 28 29 0a 7b 0a 20 20 20 69 6e 74 20 20 20 76 61 |().{. int va|
000000b0 72 31 20 3d 20 31 35 3b 0a 20 20 20 69 6e 74 20 |r1 = 15;. int |
000000c0 20 20 76 61 72 32 20 3d 20 33 34 3b 0a 20 20 20 | var2 = 34;. |
000000d0 66 6c 6f 61 74 20 66 76 61 72 20 3d 20 31 34 2e |float fvar = 14.|
000000e0 33 37 38 32 3b 0a 20 20 20 46 49 4c 45 20 20 2a |3782;. FILE *|
000000f0 66 70 6f 69 6e 74 65 72 3b 0a 20 20 20 63 68 61 |fpointer;. cha|
00000100 72 20 20 6c 65 74 74 65 72 3b 0a 0a 20 20 20 70 |r letter;.. p|
00000110 72 69 6e 74 66 28 22 70 72 69 6e 74 66 20 61 6e |rintf("printf an|
00000120 64 20 73 63 61 6e 66 20 2d 20 43 20 66 6f 72 20 |d scanf - C for |
00000130 59 6f 75 72 73 65 6c 66 20 4d 61 79 20 31 39 39 |Yourself May 199|
00000140 35 5c 6e 22 29 3b 0a 20 20 20 70 72 69 6e 74 66 |5\n");. printf|
00000150 28 22 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |("--------------|
00000160 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00000170 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 5c 6e 5c 6e |------------\n\n|
00000180 22 29 3b 0a 0a 20 20 20 70 72 69 6e 74 66 28 22 |");.. printf("|
00000190 56 61 72 69 61 62 6c 65 20 31 20 3d 20 25 64 2c |Variable 1 = %d,|
000001a0 20 76 61 72 69 61 62 6c 65 20 32 20 3d 20 25 64 | variable 2 = %d|
000001b0 2e 5c 6e 22 2c 20 76 61 72 31 2c 20 76 61 72 32 |.\n", var1, var2|
000001c0 29 3b 0a 20 20 20 70 72 69 6e 74 66 28 22 46 6c |);. printf("Fl|
000001d0 6f 61 74 69 6e 67 20 70 6f 69 6e 74 20 76 61 72 |oating point var|
000001e0 69 61 62 6c 65 20 3d 20 25 66 5c 6e 5c 6e 22 2c |iable = %f\n\n",|
000001f0 20 66 76 61 72 29 3b 0a 0a 20 20 20 70 72 69 6e | fvar);.. prin|
00000200 74 66 28 22 54 68 65 20 6c 61 73 74 20 76 61 72 |tf("The last var|
00000210 69 61 62 6c 65 20 6f 6e 6c 79 20 68 61 73 20 66 |iable only has f|
00000220 6f 75 72 20 64 65 63 69 6d 61 6c 20 70 6c 61 63 |our decimal plac|
00000230 65 73 2c 20 62 75 74 20 69 74 20 77 61 73 5c 6e |es, but it was\n|
00000240 22 29 3b 0a 20 20 20 70 72 69 6e 74 66 28 22 70 |");. printf("p|
00000250 72 69 6e 74 65 64 20 6f 75 74 20 74 6f 20 73 69 |rinted out to si|
00000260 78 2e 20 54 68 69 73 20 63 61 6e 20 62 65 20 61 |x. This can be a|
00000270 6c 74 65 72 65 64 20 62 79 20 69 6e 63 6c 75 64 |ltered by includ|
00000280 69 6e 67 20 6f 74 68 65 72 5c 6e 22 29 3b 0a 20 |ing other\n");. |
00000290 20 20 70 72 69 6e 74 66 28 22 69 6e 66 6f 72 6d | printf("inform|
000002a0 61 74 69 6f 6e 20 61 6c 6f 6e 67 20 77 69 74 68 |ation along with|
000002b0 20 74 68 65 20 63 6f 6e 76 65 72 73 69 6f 6e 20 | the conversion |
000002c0 73 70 65 63 69 66 69 65 72 73 2c 20 61 73 20 66 |specifiers, as f|
000002d0 6f 6c 6c 6f 77 73 2e 5c 6e 5c 6e 22 29 3b 0a 0a |ollows.\n\n");..|
000002e0 20 20 20 70 72 69 6e 74 66 28 22 46 6c 6f 61 74 | printf("Float|
000002f0 69 6e 67 20 70 6f 69 6e 74 20 6e 75 6d 62 65 72 |ing point number|
00000300 20 74 6f 20 34 20 64 65 63 69 6d 61 6c 20 70 6c | to 4 decimal pl|
00000310 61 63 65 73 3a 20 25 2e 34 66 5c 6e 5c 6e 22 2c |aces: %.4f\n\n",|
00000320 66 76 61 72 29 3b 0a 20 20 20 70 72 69 6e 74 66 |fvar);. printf|
00000330 28 22 54 68 69 73 20 69 73 20 68 6f 77 20 79 6f |("This is how yo|
00000340 75 20 70 72 69 6e 74 20 61 20 66 69 78 65 64 20 |u print a fixed |
00000350 77 69 64 74 68 20 66 69 65 6c 64 3a 5c 6e 22 29 |width field:\n")|
00000360 3b 0a 20 20 20 70 72 69 6e 74 66 28 22 25 37 64 |;. printf("%7d|
00000370 20 25 37 64 20 25 37 2e 34 66 5c 6e 22 2c 20 76 | %7d %7.4f\n", v|
00000380 61 72 31 2c 20 76 61 72 32 2c 20 66 76 61 72 29 |ar1, var2, fvar)|
00000390 3b 0a 20 20 20 70 72 69 6e 74 66 28 22 25 37 2e |;. printf("%7.|
000003a0 34 66 20 25 37 64 20 25 37 64 5c 6e 5c 6e 22 2c |4f %7d %7d\n\n",|
000003b0 20 66 76 61 72 2c 20 76 61 72 32 2c 20 76 61 72 | fvar, var2, var|
000003c0 31 29 3b 0a 0a 20 20 20 70 72 69 6e 74 66 28 22 |1);.. printf("|
000003d0 59 6f 75 20 63 61 6e 20 61 6c 73 6f 20 63 68 61 |You can also cha|
000003e0 6e 67 65 20 74 68 65 20 6a 75 73 74 69 66 69 63 |nge the justific|
000003f0 61 74 69 6f 6e 20 73 6f 20 74 68 61 74 20 74 68 |ation so that th|
00000400 65 20 66 69 67 75 72 65 73 20 61 72 65 5c 6e 22 |e figures are\n"|
00000410 29 3b 0a 20 20 20 70 72 69 6e 74 66 28 22 6c 65 |);. printf("le|
00000420 66 74 20 6a 75 73 74 69 66 69 65 64 2e 5c 6e 22 |ft justified.\n"|
00000430 29 3b 0a 20 20 20 70 72 69 6e 74 66 28 22 25 2d |);. printf("%-|
00000440 37 64 20 25 2d 37 64 20 25 2d 37 2e 34 66 5c 6e |7d %-7d %-7.4f\n|
00000450 5c 6e 22 2c 20 76 61 72 31 2c 20 76 61 72 32 2c |\n", var1, var2,|
00000460 20 66 76 61 72 29 3b 0a 0a 20 20 20 6c 65 74 74 | fvar);.. lett|
00000470 65 72 20 3d 20 27 42 27 3b 0a 20 20 20 70 72 69 |er = 'B';. pri|
00000480 6e 74 66 28 22 43 68 61 72 61 63 74 65 72 73 20 |ntf("Characters |
00000490 63 61 6e 20 61 6c 73 6f 20 62 65 20 70 72 69 6e |can also be prin|
000004a0 74 65 64 3a 20 25 63 5c 6e 5c 6e 22 2c 6c 65 74 |ted: %c\n\n",let|
000004b0 74 65 72 29 3b 0a 0a 20 20 20 70 72 69 6e 74 66 |ter);.. printf|
000004c0 28 22 50 6c 65 61 73 65 20 70 72 65 73 73 20 52 |("Please press R|
000004d0 45 54 55 52 4e 20 74 6f 20 63 6f 6e 74 69 6e 75 |ETURN to continu|
000004e0 65 2e 5c 6e 22 29 3b 0a 20 20 20 6c 65 74 74 65 |e.\n");. lette|
000004f0 72 20 3d 20 67 65 74 63 68 61 72 28 29 3b 0a 20 |r = getchar();. |
00000500 20 20 0a 20 20 20 70 72 69 6e 74 66 28 22 5c 66 | . printf("\f|
00000510 22 29 3b 20 2f 2a 20 54 68 69 73 20 63 6f 6e 74 |"); /* This cont|
00000520 72 6f 6c 20 63 6f 64 65 20 63 6c 65 61 72 73 20 |rol code clears |
00000530 74 68 65 20 73 63 72 65 65 6e 20 2a 2f 0a 20 20 |the screen */. |
00000540 20 70 72 69 6e 74 66 28 22 54 68 61 74 20 6c 61 | printf("That la|
00000550 73 74 20 70 72 69 6e 74 66 20 63 6c 65 61 72 65 |st printf cleare|
00000560 64 20 74 68 65 20 73 63 72 65 65 6e 20 62 79 20 |d the screen by |
00000570 75 73 69 6e 67 20 74 68 65 20 63 6f 64 65 20 5c |using the code \|
00000580 5c 66 2e 5c 6e 22 29 3b 0a 20 20 20 70 72 69 6e |\f.\n");. prin|
00000590 74 66 28 22 49 66 20 79 6f 75 20 77 61 6e 74 20 |tf("If you want |
000005a0 74 6f 20 70 72 69 6e 74 20 74 68 65 20 5c 5c 20 |to print the \\ |
000005b0 63 68 61 72 61 63 74 65 72 2c 20 75 73 65 20 5c |character, use \|
000005c0 5c 5c 5c 20 61 73 20 74 68 65 20 63 6f 6e 74 72 |\\\ as the contr|
000005d0 6f 6c 20 63 6f 64 65 2e 5c 6e 5c 6e 22 29 3b 0a |ol code.\n\n");.|
000005e0 20 20 20 70 72 69 6e 74 66 28 22 50 6c 65 61 73 | printf("Pleas|
000005f0 65 20 65 6e 74 65 72 20 61 20 6e 65 77 20 69 6e |e enter a new in|
00000600 74 65 67 65 72 20 66 6f 72 20 76 61 72 31 3a 5c |teger for var1:\|
00000610 6e 22 29 3b 0a 20 20 20 73 63 61 6e 66 28 22 25 |n");. scanf("%|
00000620 64 22 2c 20 26 76 61 72 31 29 3b 0a 20 20 20 77 |d", &var1);. w|
00000630 68 69 6c 65 20 28 67 65 74 63 68 61 72 28 29 20 |hile (getchar() |
00000640 21 3d 20 27 5c 6e 27 29 3b 0a 20 20 20 70 72 69 |!= '\n');. pri|
00000650 6e 74 66 28 22 4e 6f 77 2c 20 70 6c 65 61 73 65 |ntf("Now, please|
00000660 20 65 6e 74 65 72 20 61 6e 6f 74 68 65 72 20 69 | enter another i|
00000670 6e 74 65 67 65 72 20 66 6f 72 20 76 61 72 32 3a |nteger for var2:|
00000680 5c 6e 22 29 3b 0a 20 20 20 73 63 61 6e 66 28 22 |\n");. scanf("|
00000690 25 64 22 2c 20 26 76 61 72 32 29 3b 0a 20 20 20 |%d", &var2);. |
000006a0 77 68 69 6c 65 20 28 67 65 74 63 68 61 72 28 29 |while (getchar()|
000006b0 20 21 3d 20 27 5c 6e 27 29 3b 0a 20 20 20 70 72 | != '\n');. pr|
000006c0 69 6e 74 66 28 22 46 69 6e 61 6c 6c 79 2c 20 70 |intf("Finally, p|
000006d0 6c 65 61 73 65 20 65 6e 74 65 72 20 61 20 66 6c |lease enter a fl|
000006e0 6f 61 74 69 6e 67 20 70 6f 69 6e 74 20 6e 75 6d |oating point num|
000006f0 62 65 72 20 66 6f 72 20 66 76 61 72 3a 5c 6e 22 |ber for fvar:\n"|
00000700 29 3b 0a 20 20 20 73 63 61 6e 66 28 22 25 66 22 |);. scanf("%f"|
00000710 2c 26 66 76 61 72 29 3b 0a 20 20 20 77 68 69 6c |,&fvar);. whil|
00000720 65 20 28 67 65 74 63 68 61 72 28 29 20 21 3d 20 |e (getchar() != |
00000730 27 5c 6e 27 29 3b 0a 0a 0a 20 20 20 69 66 20 28 |'\n');... if (|
00000740 28 66 70 6f 69 6e 74 65 72 20 3d 20 66 6f 70 65 |(fpointer = fope|
00000750 6e 28 22 74 65 73 74 66 69 6c 65 22 2c 22 77 22 |n("testfile","w"|
00000760 29 29 20 3d 3d 20 30 29 20 7b 0a 20 20 20 20 20 |)) == 0) {. |
00000770 20 70 72 69 6e 74 66 28 22 46 69 6c 65 20 6f 70 | printf("File op|
00000780 65 6e 20 66 61 69 6c 65 64 2e 20 50 6c 65 61 73 |en failed. Pleas|
00000790 65 20 63 68 61 6e 67 65 20 64 69 72 65 63 74 6f |e change directo|
000007a0 72 79 20 74 6f 20 6f 6e 65 20 77 68 69 63 68 20 |ry to one which |
000007b0 68 61 73 20 77 72 69 74 65 20 61 63 63 65 73 73 |has write access|
000007c0 2e 5c 6e 22 29 3b 0a 20 20 20 20 20 20 72 65 74 |.\n");. ret|
000007d0 75 72 6e 3b 0a 20 20 20 7d 0a 20 20 20 66 70 72 |urn;. }. fpr|
000007e0 69 6e 74 66 28 66 70 6f 69 6e 74 65 72 2c 20 22 |intf(fpointer, "|
000007f0 54 68 69 73 20 69 73 20 73 6f 6d 65 20 74 65 78 |This is some tex|
00000800 74 2c 20 61 6e 64 20 74 68 69 73 20 69 73 20 76 |t, and this is v|
00000810 61 72 69 61 62 6c 65 20 31 3a 20 25 64 5c 6e 22 |ariable 1: %d\n"|
00000820 2c 20 76 61 72 31 29 3b 0a 20 20 20 66 70 72 69 |, var1);. fpri|
00000830 6e 74 66 28 66 70 6f 69 6e 74 65 72 2c 20 22 56 |ntf(fpointer, "V|
00000840 61 72 69 61 62 6c 65 20 32 3a 20 25 64 5c 6e 46 |ariable 2: %d\nF|
00000850 6c 6f 61 74 69 6e 67 20 70 6f 69 6e 74 20 76 61 |loating point va|
00000860 72 69 61 62 6c 65 3a 20 25 2e 34 66 5c 6e 22 2c |riable: %.4f\n",|
00000870 20 76 61 72 32 2c 20 66 76 61 72 29 3b 0a 20 20 | var2, fvar);. |
00000880 20 69 66 20 28 66 63 6c 6f 73 65 28 66 70 6f 69 | if (fclose(fpoi|
00000890 6e 74 65 72 29 20 21 3d 20 30 29 20 7b 0a 20 20 |nter) != 0) {. |
000008a0 20 20 20 20 70 72 69 6e 74 66 28 22 46 69 6c 65 | printf("File|
000008b0 20 63 6c 6f 73 65 20 66 61 69 6c 65 64 2e 20 53 | close failed. S|
000008c0 6f 72 72 79 21 5c 6e 22 29 3b 0a 20 20 20 7d 20 |orry!\n");. } |
000008d0 65 6c 73 65 20 7b 0a 20 20 20 20 20 20 70 72 69 |else {. pri|
000008e0 6e 74 66 28 22 41 20 74 65 78 74 20 66 69 6c 65 |ntf("A text file|
000008f0 20 63 61 6c 6c 65 64 20 5c 27 74 65 73 74 66 69 | called \'testfi|
00000900 6c 65 5c 27 20 68 61 73 20 6a 75 73 74 20 62 65 |le\' has just be|
00000910 65 6e 20 63 72 65 61 74 65 64 20 69 6e 20 74 68 |en created in th|
00000920 65 20 63 75 72 72 65 6e 74 20 64 69 72 65 63 74 |e current direct|
00000930 6f 72 79 2e 5c 6e 22 29 3b 0a 20 20 20 20 20 20 |ory.\n");. |
00000940 70 72 69 6e 74 66 28 22 54 72 79 20 6c 6f 61 64 |printf("Try load|
00000950 69 6e 67 20 69 74 20 69 6e 74 6f 20 45 64 69 74 |ing it into Edit|
00000960 2e 2e 2e 5c 6e 22 29 3b 0a 20 20 20 7d 0a 7d 0a |...\n");. }.}.|
00000970 0a |.|
00000971 
.