C choosing variable type at run-time
I have this piece of code below which seems very explicit and redundant, is there a way to choose variable type at run-time?
if(header->bitsPerSample == 16) {
int sample;
for (int i = 0; i < header->chunkSize - HEADER_SIZE + 8; i += sizeof(sample) * 2) {
fread(&sample, sizeof(sample), 1, fp);
fwrite(&sample, sizeof(sample), 1, new);
fread(&sample, sizeof(sample), 1, fp);
}
} else if(header->bitsPerSample == 8) {
char sample;
for (int i = 0; i < header->chunkSize - HEADER_SIZE + 8; i += sizeof(sample) * 2) {
fread(&sample, sizeof(sample), 1, fp);
fwrite(&sample, sizeof(sample), 1, new);
fread(&sample, sizeof(sample), 1, fp);
}
}
I'm looking for something like this:
if(header->bitsPerSample == 16)
sample is of type int
else if(header->bitsPerSample == 8)
sample is of type char
for (int i = 0; i < header->chunkSize - HEADER_SIZE + 8; i += sizeof(sample) * 2) {
fread(&sample, sizeof(sample), 1, fp);
fwrite(&sample, sizeof(sample), 1, new);
fread(&sample, sizeof(sample), 1, fp);
}
c syntactic-sugar
asked Nov 15 '18 at 16:22
Aristos GeorgiouAristos Georgiou
1089
add a comment |
I have this piece of code below which seems very explicit and redundant, is there a way to choose variable type at run-time?
if(header->bitsPerSample == 16) {
int sample;
for (int i = 0; i < header->chunkSize - HEADER_SIZE + 8; i += sizeof(sample) * 2) {
fread(&sample, sizeof(sample), 1, fp);
fwrite(&sample, sizeof(sample), 1, new);
fread(&sample, sizeof(sample), 1, fp);
}
} else if(header->bitsPerSample == 8) {
char sample;
for (int i = 0; i < header->chunkSize - HEADER_SIZE + 8; i += sizeof(sample) * 2) {
fread(&sample, sizeof(sample), 1, fp);
fwrite(&sample, sizeof(sample), 1, new);
fread(&sample, sizeof(sample), 1, fp);
}
}
I'm looking for something like this:
if(header->bitsPerSample == 16)
sample is of type int
else if(header->bitsPerSample == 8)
sample is of type char
for (int i = 0; i < header->chunkSize - HEADER_SIZE + 8; i += sizeof(sample) * 2) {
fread(&sample, sizeof(sample), 1, fp);
fwrite(&sample, sizeof(sample), 1, new);
fread(&sample, sizeof(sample), 1, fp);
}
c syntactic-sugar
asked Nov 15 '18 at 16:22
Aristos GeorgiouAristos Georgiou
1089
2
Types in C are only known at compile time. You might want tagged unions, and you'll build them abovestructandunion
– Basile Starynkevitch
Nov 15 '18 at 16:31
add a comment |
I have this piece of code below which seems very explicit and redundant, is there a way to choose variable type at run-time?
if(header->bitsPerSample == 16) {
int sample;
for (int i = 0; i < header->chunkSize - HEADER_SIZE + 8; i += sizeof(sample) * 2) {
fread(&sample, sizeof(sample), 1, fp);
fwrite(&sample, sizeof(sample), 1, new);
fread(&sample, sizeof(sample), 1, fp);
}
} else if(header->bitsPerSample == 8) {
char sample;
for (int i = 0; i < header->chunkSize - HEADER_SIZE + 8; i += sizeof(sample) * 2) {
fread(&sample, sizeof(sample), 1, fp);
fwrite(&sample, sizeof(sample), 1, new);
fread(&sample, sizeof(sample), 1, fp);
}
}
I'm looking for something like this:
if(header->bitsPerSample == 16)
sample is of type int
else if(header->bitsPerSample == 8)
sample is of type char
for (int i = 0; i < header->chunkSize - HEADER_SIZE + 8; i += sizeof(sample) * 2) {
fread(&sample, sizeof(sample), 1, fp);
fwrite(&sample, sizeof(sample), 1, new);
fread(&sample, sizeof(sample), 1, fp);
}
c syntactic-sugar
asked Nov 15 '18 at 16:22
Aristos GeorgiouAristos Georgiou
1089
I have this piece of code below which seems very explicit and redundant, is there a way to choose variable type at run-time?
if(header->bitsPerSample == 16) {
int sample;
for (int i = 0; i < header->chunkSize - HEADER_SIZE + 8; i += sizeof(sample) * 2) {
fread(&sample, sizeof(sample), 1, fp);
fwrite(&sample, sizeof(sample), 1, new);
fread(&sample, sizeof(sample), 1, fp);
}
} else if(header->bitsPerSample == 8) {
char sample;
for (int i = 0; i < header->chunkSize - HEADER_SIZE + 8; i += sizeof(sample) * 2) {
fread(&sample, sizeof(sample), 1, fp);
fwrite(&sample, sizeof(sample), 1, new);
fread(&sample, sizeof(sample), 1, fp);
}
}
I'm looking for something like this:
if(header->bitsPerSample == 16)
sample is of type int
else if(header->bitsPerSample == 8)
sample is of type char
for (int i = 0; i < header->chunkSize - HEADER_SIZE + 8; i += sizeof(sample) * 2) {
fread(&sample, sizeof(sample), 1, fp);
fwrite(&sample, sizeof(sample), 1, new);
fread(&sample, sizeof(sample), 1, fp);
}
c syntactic-sugar
c syntactic-sugar
asked Nov 15 '18 at 16:22
Aristos GeorgiouAristos Georgiou
1089
asked Nov 15 '18 at 16:22
Aristos GeorgiouAristos Georgiou
1089
asked Nov 15 '18 at 16:22
Aristos GeorgiouAristos Georgiou
1089
asked Nov 15 '18 at 16:22
Aristos GeorgiouAristos Georgiou
1089
asked Nov 15 '18 at 16:22
Aristos GeorgiouAristos Georgiou
1089
1089
2
Types in C are only known at compile time. You might want tagged unions, and you'll build them abovestructandunion
– Basile Starynkevitch
Nov 15 '18 at 16:31
add a comment |
2
Types in C are only known at compile time. You might want tagged unions, and you'll build them abovestructandunion
– Basile Starynkevitch
Nov 15 '18 at 16:31
2
2
Types in C are only known at compile time. You might want tagged unions, and you'll build them above
struct and union– Basile Starynkevitch
Nov 15 '18 at 16:31
Types in C are only known at compile time. You might want tagged unions, and you'll build them above
struct and union– Basile Starynkevitch
Nov 15 '18 at 16:31
add a comment |
2 Answers
2
active
oldest
votes
C's only tool for writing generic code is with macros, but that's not necessary here.
Skip the formality of declaring a variable of precisely the right type and instead just read or write the appropriate number of bytes:
size_t raw_size = header->bitsPerSample / 8;
unsigned char buffer[raw_size];
void* raw = &buffer;
for (int i = 0; i < header->chunkSize - HEADER_SIZE + 8; i += raw_size * 2) {
fread(raw, raw_size, 1, fp);
fwrite(raw, raw_size, 1, new);
fread(raw, raw_size, 1, fp);
}
Since your code doesn't really care what the values are, just how many bytes they require, you can just use character buffers.
answered Nov 15 '18 at 16:30
tadmantadman
156k18178209
add a comment |
You cannot do this, I suggest you to use the same variable type, for example you can cast a int to char and you will reach the correct value
answered Nov 15 '18 at 16:28
Alesandro GiordanoAlesandro Giordano
318110
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
C's only tool for writing generic code is with macros, but that's not necessary here.
Skip the formality of declaring a variable of precisely the right type and instead just read or write the appropriate number of bytes:
size_t raw_size = header->bitsPerSample / 8;
unsigned char buffer[raw_size];
void* raw = &buffer;
for (int i = 0; i < header->chunkSize - HEADER_SIZE + 8; i += raw_size * 2) {
fread(raw, raw_size, 1, fp);
fwrite(raw, raw_size, 1, new);
fread(raw, raw_size, 1, fp);
}
Since your code doesn't really care what the values are, just how many bytes they require, you can just use character buffers.
answered Nov 15 '18 at 16:30
tadmantadman
156k18178209
add a comment |
C's only tool for writing generic code is with macros, but that's not necessary here.
Skip the formality of declaring a variable of precisely the right type and instead just read or write the appropriate number of bytes:
size_t raw_size = header->bitsPerSample / 8;
unsigned char buffer[raw_size];
void* raw = &buffer;
for (int i = 0; i < header->chunkSize - HEADER_SIZE + 8; i += raw_size * 2) {
fread(raw, raw_size, 1, fp);
fwrite(raw, raw_size, 1, new);
fread(raw, raw_size, 1, fp);
}
Since your code doesn't really care what the values are, just how many bytes they require, you can just use character buffers.
answered Nov 15 '18 at 16:30
tadmantadman
156k18178209
add a comment |
C's only tool for writing generic code is with macros, but that's not necessary here.
Skip the formality of declaring a variable of precisely the right type and instead just read or write the appropriate number of bytes:
size_t raw_size = header->bitsPerSample / 8;
unsigned char buffer[raw_size];
void* raw = &buffer;
for (int i = 0; i < header->chunkSize - HEADER_SIZE + 8; i += raw_size * 2) {
fread(raw, raw_size, 1, fp);
fwrite(raw, raw_size, 1, new);
fread(raw, raw_size, 1, fp);
}
Since your code doesn't really care what the values are, just how many bytes they require, you can just use character buffers.
answered Nov 15 '18 at 16:30
tadmantadman
156k18178209
C's only tool for writing generic code is with macros, but that's not necessary here.
Skip the formality of declaring a variable of precisely the right type and instead just read or write the appropriate number of bytes:
size_t raw_size = header->bitsPerSample / 8;
unsigned char buffer[raw_size];
void* raw = &buffer;
for (int i = 0; i < header->chunkSize - HEADER_SIZE + 8; i += raw_size * 2) {
fread(raw, raw_size, 1, fp);
fwrite(raw, raw_size, 1, new);
fread(raw, raw_size, 1, fp);
}
Since your code doesn't really care what the values are, just how many bytes they require, you can just use character buffers.
answered Nov 15 '18 at 16:30
tadmantadman
156k18178209
edited Nov 15 '18 at 19:06
answered Nov 15 '18 at 16:30
tadmantadman
156k18178209
answered Nov 15 '18 at 16:30
tadmantadman
156k18178209
answered Nov 15 '18 at 16:30
tadmantadman
156k18178209
156k18178209
add a comment |
add a comment |
You cannot do this, I suggest you to use the same variable type, for example you can cast a int to char and you will reach the correct value
answered Nov 15 '18 at 16:28
Alesandro GiordanoAlesandro Giordano
318110
add a comment |
You cannot do this, I suggest you to use the same variable type, for example you can cast a int to char and you will reach the correct value
answered Nov 15 '18 at 16:28
Alesandro GiordanoAlesandro Giordano
318110
add a comment |
You cannot do this, I suggest you to use the same variable type, for example you can cast a int to char and you will reach the correct value
answered Nov 15 '18 at 16:28
Alesandro GiordanoAlesandro Giordano
318110
You cannot do this, I suggest you to use the same variable type, for example you can cast a int to char and you will reach the correct value
answered Nov 15 '18 at 16:28
Alesandro GiordanoAlesandro Giordano
318110
answered Nov 15 '18 at 16:28
Alesandro GiordanoAlesandro Giordano
318110
answered Nov 15 '18 at 16:28
Alesandro GiordanoAlesandro Giordano
318110
answered Nov 15 '18 at 16:28
Alesandro GiordanoAlesandro Giordano
318110
318110
add a comment |
add a comment |
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2
Types in C are only known at compile time. You might want tagged unions, and you'll build them above
structandunion– Basile Starynkevitch
Nov 15 '18 at 16:31