Avatar
[acool@localhost ~]$
[acool@localhost ~]$ date
Mon Apr 3 11:17:50 AM PDT 2023
[acool@localhost ~]$
[acool@localhost ~]$ cat c-foreach-macro.c
#include <stdio.h>
#define foreach(item, array) \
for(int keep = 1, \
count = 0,\
size = sizeof (array) / sizeof *(array); \
keep && count != size; \
keep = !keep, count++) \
for(item = (array) + count; keep; keep = !keep)
int main()
{
int mynumbers[] = {5,20,35,62,8,74,89};
char mygreeting[] = {"Hello world!"};
float myfloats[] = {1.6,6.9,5.8,43.5,1.1,0.9};
foreach(int *v, mynumbers) {
printf("value: %d\n", *v);
}
foreach(char *v, mygreeting) {
printf("value: %c\n", *v);
}
foreach(float *v, myfloats) {
printf("value: %.2f\n", *v);
}
return 0;
}
[acool@localhost ~]$
[acool@localhost ~]$ gcc c-foreach-macro.c -o c-foreach-macro
[acool@localhost ~]$
[acool@localhost ~]$ ./c-foreach-macro
value: 5
value: 20
value: 35
value: 62
value: 8
value: 74
value: 89
value: H
value: e
value: l
value: l
value: o
value:
value: w
value: o
value: r
value: l
value: d
value: !
value:
value: 1.60
value: 6.90
value: 5.80
value: 43.50
value: 1.10
value: 0.90
[acool@localhost ~]$
Bonus - dumping output from preprocessor.
[acool@localhost ~]$
[acool@localhost ~]$ gcc c-foreach-macro.c -E -o c-macro.preprocessed
[acool@localhost ~]$
[acool@localhost ~]$ cat c-macro.preprocessed
...
int main()
{
int mynumbers[] = {5,20,35,62,8,74,89};
char mygreeting[] = {"Hello world!"};
float myfloats[] = {1.6,6.9,5.8,43.5,1.1,0.9};
for(int keep = 1, count = 0, size = sizeof (mynumbers) / sizeof *(mynumbers); keep && count != size; keep = !keep, count++) for(int *v = (mynumbers) + count; keep; keep = !keep) {
printf("value: %d\n", *v);
}
for(int keep = 1, count = 0, size = sizeof (mygreeting) / sizeof *(mygreeting); keep && count != size; keep = !keep, count++) for(char *v = (mygreeting) + count; keep; keep = !keep) {
printf("value: %c\n", *v);
}
for(int keep = 1, count = 0, size = sizeof (myfloats) / sizeof *(myfloats); keep && count != size; keep = !keep, count++) for(float *v = (myfloats) + count; keep; keep = !keep) {
printf("value: %.2f\n", *v);
}
return 0;
}
[acool@localhost ~]$
Comments
Comments are not available for this entry.