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HamCall (April 1991)
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HAMCALL CD-ROM (Buckmaster)(April 1991).BIN
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prgming
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ctutor
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uplow.c
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1990-10-14
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/* Chapter 13 - Program 1 */
#include "STDIO.H"
#include "ctype.h" /* Note - your compiler may not need this */
main()
{
FILE *fp;
char line[80], filename[24];
char *c;
printf("Enter filename -> ");
scanf("%s",filename);
fp = fopen(filename,"r");
do {
c = fgets(line,80,fp); /* get a line of text */
if (c != NULL) {
mix_up_the_chars(line);
}
} while (c != NULL);
fclose(fp);
}
mix_up_the_chars(line) /* this function turns all upper case
characters into lower case, and all
lower case to upper case. It ignores
all other characters. */
char line[];
{
int index;
for (index = 0;line[index] != 0;index++) {
if (isupper(line[index])) /* 1 if upper case */
line[index] = tolower(line[index]);
else {
if (islower(line[index])) /* 1 if lower case */
line[index] = toupper(line[index]);
}
}
printf("%s",line);
}
/* Result of execution
(The selected file is displayed on the monitor with all of
the upper case characters converted to lower case, and all
of the lower case characters converted to upper case.)
*/