These 2 consonants follow the same rule.
Their pronunciations depend on the letter that follows.
Hard sound
A
O
U
Consonants
C
canne
corde
cuve
crème
G
gars
gorille
guêt
gras
Soft sound
E
I
Y
C
ce
ci
cygne
G
gens
gitan
gymnaste
C with an accent (called a cedilla) makes it a soft C.
Ç
as in
ça
CH is like the English 'SH', except when it is followed by another consonant (it is then pronounced like 'K').
CH
as in
chaud
CH
as in
chrétien
G followed by a 'N' makes a nasal sound.
GN
as in
mignon
H
H is generally silent.
H
as in
homme
L
Double L is generally pronounced like Y, but sometimes like a normal L. This varies on a case by case basis and there is no general rule. Compare the two examples below:
L
as in
langue
LL
as in
fille
LL
as in
mille
P
Unlike English, P is not silent when followed by S or N.
P
as in
poule
PS
as in
psychologie
PN
as in
pneu
S
S is generally pronounced like in English, except when it comes between two vowels, it is pronounced like 'Z'.
S
as in
sel
S
as in
misère
T
T and TH are pronounced the same. TI followed by another vowel sounds like 'see'.
T
as in
titre
TH
as in
thé
TI
as in
fonction
X
X is either pronunced as in English, or with a GZ sound.
X
as in
taxe
X
as in
exemple
W
W is rare in French and only found in borrowed words. It is pronounced like either V or W, depending on which language the word is borrowed from.
W
as in
week-end (English)
W
as in
wagon (German)
Final letter
Consonants are often silent at the end of French words, but not always. There is no rule, it just varies on a word-by-word basis. Below are some common examples.